Gears were, in the early days, like bearings: very magical things. According to the scientific understanding of the time, they could not possibly work. The faces of two gears touching can be approximately represented as a single line contact of infinite ‘thin-ness’ along the faces of the gears. When you calculated the forces acting here, they were of course infinite (the line having no area, and the equation for stress being sigma=force/area). This was very upsetting for early gear pioneers, who were pleased when German physicist Heinrich Hertz published Über die Berührung fester elastischer Körper (On the contact of solid elastic bodies).1 

Hertz’s work accurately determined that two circles forced together actually ‘squidge’, resulting in a much larger contact area than might be expected. This became known as the Hertz Contact Theory, and is still used today.

Engineers were happy that the stresses in their gears now seemed to be below the level at which the gears ought to break. However, they were most vexed by the fact that their calculations showed that the gears which had worked for decades could not possibly work for any sustained length of time. This was because gears need a lubricant to stop the teeth rubbing together, and the calculations still stubbornly showed that even with the now much larger contact zone as predicted by Hertz, the level of the oil film was far below the rough surfaces of the teeth. This meant that the oil couldn’t keep the surfaces apart – they ought to tear themselves to shreds in hours.

In around 1893, Carl Barus came to the rescue with the theory now known as the Barus Law. This stated that – to everyone’s great surprise – the factor in an oil that stops it getting flattened by pressure (its viscosity) doesn’t just go up the more you press it between two contacts, it actually skyrockets. This meant that if you added Hertz’s realization that two cylinders touching don’t really contact as a ‘line’ to the fact that the oil viscosity in this wider contact was considerably higher than expected from simple lab tests on oils, suddenly gears and bearings made sense to those trying to calculate their behavior.

However, the engineering world took a while to start putting these pieces together. This was possibly because without the Barus Law being added to it, Hertz’s work didn’t make sense for gear contacts. Without the exponential increase in viscosity inside the contact zone, the oil film was not predicted to survive the pressures needed to deform the steel contacts elastically.

Then, at Moscow Central Institute for Mechanical Engineering, Alexander Ertel-Morenstein became the first to combine the work of Hertz (elastic deformation) with hydrodynamics and tribology (existing fluids laws added to the Barus Law). Thus, the field of elastohydrodynamics was born, where the correct contact width was known, due to Hertz; the correct fluid viscosity under pressure was known (thanks to Barus); and equations showed how all this combined in a gear contact, revealing that the real oil film thickness was higher than the roughness of the metal underneath. 

The problem was, Ertel had been doing much of this work in Russia during World War II. By now he was desperately sick with tuberculosis, and no one outside the country knew of his research. In 1945 he wrote The Calculation of Hydrodynamic Lubrication of Moving Curved Surfaces under High Loading, about which Dr A N Grubin, the head of the institute’s bearings department, stated, “The level of this work approaches that of the classical works of the lubrication theories by Petrov, Reynolds, Hertz.” Anyone who knows anything about Russians and mathematics understands that this meant it was very difficult work indeed.

By the time the war ended, Ertel was incredibly ill. Taking advantage of a posting to East Berlin, he reportedly faked his own death in a swimming accident and defected to the West, where he was welcomed and restored to health.

To keep his existence a secret from the Russian authorities, he assumed the alias Alexander von Mohrenstein (adding ‘von’ for a more convincing Germanic feel) and began work under Prof. Gustav Niemann at TH Braunschweig. His groundbreaking paper was published in 1949 under the name of his former head of department, Dr Grubin.

In 1966, Prof. M M Khrushchev at Moscow Central Institute for Mechanical Engineering received a letter from Ertel, which said, “In Grubin’s paper, there is no mention that the theory and calculations were conducted by me. I find this very indecent of him. However, should you see Grubin, tell him that I have forgiven him. With kind regards, your A Ertel (Dr A Morenstein).”

In my own undergraduate thesis I used the ‘Grubin’ method to calculate gear oil film thickness. It was only in the last few years that I discovered that it was not really Grubin who worked out how (and why) gears and bearings work.

Ertel lived a long life and died in 2001. Most people who have investigated the story believe that Grubin probably did not seek to plagiarize him. Aware of the importance of the work, he knew it had to be disseminated in the West. However, it could not be published under Ertel’s name for fear of bringing him to the attention of the NKVD (Russian security services), who would not be best pleased that one of the country’s top scientists had run away and been given a nice job working for the capitalists. Thus, Grubin published it under his own name to protect Ertel. The whole story was finally revealed after exhaustive research by the English tribologist Prof. A Cameron, published in the article Righting a 40-year-old wrong: A. M. Ertel – the true author of ‘Grubin’s EHL’ Solution, Tribology Int. 18, 92 (1985).

1) https://home.uni-leipzig.de/pwm/web/download/Hertz1881.pdf

As manufacturers push for shorter development cycles, reliance on virtual engineering and validation is growing fast. High-fidelity simulation and model-based design allow teams to iterate concepts more quickly than ever, but physical testing remains a vital part of the development chain. Rob Smith, head of development and test at propulsion system development partner Drive System Design, explores physical and virtual testing

Physical tests at any level introduce risks. These include logistical and planning challenges, as well as additional program costs.  Despite this, the demand for focused testing to support model correlation is increasing. Robust design verification (DV) and product validation (PV) programs remain non‑negotiable, underpinning confidence in product safety and performance.

The purpose of physical testing

Testing has always been a necessary way to quantify and assess many aspects of a product’s performance and characteristics.

Physical test results have long been the benchmark against which computer-aided engineering (CAE) models are correlated – a necessary step to ensure simulations represent reality for the full range of operating conditions.

Recent trends

With ever-improving computational power, product development programs are increasingly starting with the creation of digital twins, which are high‑fidelity, virtual representations of physical systems or components. Rather than acting solely as a pass/fail assessment, early test cycles are now tailored to strengthen model accuracy – deliberately selected load cases, boundary conditions and sensor arrays feed the virtual model with targeted data.

Test phases often mirror elements of conventional DV plans, but with a different emphasis, focusing on correlation points and characterization boundaries that make the digital twin trustworthy across the design space. That can mean smaller, more impactful tests executed quickly and iterated frequently.

Reducing risk through early virtual correlation

While physical testing is still a necessary part of any development program, early correlation with virtual models and simulations minimizes technical, fiscal, logistical and schedule risks. Issues discovered late in a program or close to production are far more expensive to fix and can jeopardize launch timelines. In extreme cases, they can even damage consumer confidence and brand reputation.

Equally important is the less quantifiable but critical return on investment – confidence. Confidence to scale production, to pass certification cycles with fewer surprises, and to stand behind a product in service. Well-executed test programs reduce uncertainty. They give engineering, manufacturing and business stakeholders the evidence to make faster, bolder decisions.

Will digital twins replace the need for physical tests?

Digital twins are powerful accelerants. They let engineers explore options, run virtual what‑if scenarios and optimize systems faster than physical prototypes allow. But regardless of how well correlated they are, digital twins cannot capture every real‑world uncertainty.

There are factors that can only arise during physical testing, such as manufacturing variability, material property deviations or defects, and subtle system‑to‑system interactions. These can defeat even the best virtual model. Some sectors – aerospace is a notable example – have tightly controlled material processes that reduce this uncertainty, but that control comes at the expense of longer development cycles and higher cost.

Physical testing is the data source that validates and calibrates digital twins. It supplies ground truth for material behaviors, component interactions and environmental influences. In turn, validated digital twins enable predictive maintenance strategies, support virtual certification scenarios and let teams explore failure modes that would be destructive or impractical to test physically. The sooner a manufacturer can build and trust a digital twin, the more effective and efficient the subsequent development cycles become.

What can we expect in the future of testing?

The pace of testing progress will be driven by two technical shifts: increased modeling capability and faster, higher‑quality test data.

Modeling is becoming more accessible. Computational power and improved numerical methods now make it commercially viable to model fluid systems and thermal‑mechanical interactions that were once prohibitively expensive. Improved simulation of splash lubrication, transient cooling and multi‑physics coupling is already narrowing gaps to physical testing.

Real‑time processing and near‑continuous model updates will become standard practice. This places new demands on instrumentation, automation and test engineers. To capitalize on shorter development cycles, test systems must deliver reliable data at much higher rates and with faster post‑processing.

An example from development practice is a highly automated maximum torque per amp (MTPA) optimization routine. By combining machine learning, advanced test equipment and in‑house control and automation systems, it is possible to iterate tens of thousands of operating points in a matter of days. This delivers processed results ready for immediate analysis, which can be fed back into digital twins quickly, shortening the loop between hypothesis, test and update.

We should also expect innovation in measurement techniques and sensors. Telemetry solutions for rotor temperature, non‑intrusive torque measurements, and compact, high‑accuracy speed sensors are examples that will enable new test regimes. Treating test capability as strategic infrastructure by investing in well‑designed assets, integrating them into early design phases and using their data to feed both physical and virtual models will be essential.

Testing as a strategic enabler

Testing is often seen as a validation chore at the end of development. In a world of digital twins and rapid iteration, testing should be reframed as an enabler. It can be the provider of trusted data that lets virtual engineering unlock value.

The future will not see physical testing disappear. It will see testing become faster, more expansive in terms of data acquired, and more deeply integrated with simulation. This shift will reduce program risk, speed up time-to-market and, ultimately, enable the kind of propulsion innovation the industry continues to demand.

For engineers and program leads, the practical takeaway is simple: treat physical development testing as strategic. Build virtual model correlation into early test plans, invest in the right instrumentation and test equipment, and use those test results to mature digital twins as early as possible. Do that, and testing will shift from a necessary overhead into a competitive advantage.

In related news, Ideal Semiconductor launches MOSFET for efficiency and safety in high-voltage battery systems

The UK’s adoption of Euro 6e-bis emissions standards from April 2026 will represent a shift in how plug-in hybrid vehicles must be tested and validated during development. While original equipment manufacturers (OEMs) have been planning for this transition with increasing battery sizes for plug-in hybrid electric vehicles (PHEVs), the stagnating private purchases of electric vehicles (EVs) mean OEMs need to consider the increasing demand for PHEVs and focus on improving internal combustion engine (ICE) efficiency and increasing EV efficiency alongside larger batteries. Vehicles currently progressing through validation cycles may need complete recalibration to avoid catastrophic CO₂ rating increases.

At Mahle Powertrain, we already work to EU standards while maintaining comprehensive UK certification capabilities. This gives us clear visibility into what’s coming. We’re seeing PHEVs that would achieve 10g/km CO₂ ratings under current UK protocols potentially jumping to 30g/km or higher under Euro 6e-bis utility factor calculations. This is a fundamental change that demands immediate attention from pre-production testing teams.

The challenge is particularly acute because the new standards don’t just change the final compliance testing; they alter the calculation of the OEM fleet average CO₂, causing PHEVs to contribute more to this fleet average CO₂. This means OEMs have to sell more EV vehicles in a period of low consumer demand or improve the efficiency of the ICE and EV systems in PHEV and hybrid applications. OEMs continuing to develop PHEVs using current UK testing methodologies risk discovering compliance issues too late in the development cycle to implement cost-effective solutions.

Understanding utility factor calculations               

The core of Euro 6e-bis lies in utility factor calculations, which alter how plug-in hybrid vehicles are assessed during type approval. Under current UK regulations, PHEVs undertake straightforward charge-depleting and charge-sustaining test cycles that produce CO₂ figures that are not representative of all use cases. Euro 6e-bis introduces an updated calculation that biases the calculation toward the ICE operation of the vehicle, therefore placing increased relevance on ICE efficiency.

From our technology-agnostic testing experience, the utility factor methodology considers how frequently drivers actually charge their PHEVs, applying statistical weighting to different driving scenarios. This means that a PHEV designed and validated under current UK protocols could see its official CO₂ rating triple when subjected to Euro 6e-bis testing, even without any changes to the vehicle itself.

For pre-production testing teams, this focus on ICE and EV efficiency creates immediate challenges. At Mahle, we’re addressing this through our range extender (REx) and advanced battery systems technology, which allows us to optimize both electric range and charge-sustaining performance to meet the new requirements.

Validation timelines and fleet average impact

The transition to Euro 6e-bis creates significant challenges around OEM fleet average CO₂ compliance, particularly given consumer apathy toward private EV purchases. The issue for OEMs is the fast implementation of the UK regulation, which needs careful planning to ensure there are no fleet average CO₂ exceedances – a significant risk when considering what consumers currently want to purchase.

We’re working with several OEMs to understand how the new testing protocols will affect their ability to meet fleet targets while satisfying market demand. The emphasis on improving ICE efficiency and implementing improved battery technology becomes critical when PHEVs contribute more heavily to fleet averages under the new calculation methods.

OEMs with PHEVs planned for launch in late 2026 or early 2027 face strategic decisions about powertrain development priorities. Euro 6e-bis requires different approaches to ICE optimization and battery system integration.

Progressive OEMs are implementing strategies that account for regulatory compliance and market realities; powertrain configurations that can achieve acceptable fleet average contributions while meeting consumer expectations for PHEV performance.

Changing PHEV development processes

Forward-thinking OEMs are implementing Euro 6e-bis validation throughout development processes, with Mahle’s ICE efficiency and REx/PHEV technology providing crucial capabilities for customers navigating this transition. Our range extender technology and advanced battery systems allow OEMs to achieve the balance between electric efficiency and ICE performance that Euro 6e-bis demands.

The process changes extend beyond testing protocols to encompass fundamental powertrain architecture decisions. PHEV concepts that work well under current UK regulations may be fundamentally unsuited to Euro 6e-bis requirements, making early validation crucial for avoiding costly late-stage changes.

We’re seeing OEMs revisit their PHEV portfolio strategies in light of both Euro 6e-bis requirements and market demand patterns. Our REx and battery technology solutions help OEMs develop powertrains that can meet the new utility factor calculations while delivering the performance characteristics consumers expect.

For Mahle Powertrain, our early adoption of Euro 6e-bis testing protocols positions us to support OEMs through this transition. Our dual UK-EU testing capabilities allow us to provide comparative analysis that helps OEMs understand the specific implications of EU6e and beyond, along with global regulations, for their vehicle programs.

To ensure that OEMs have the correct fleet mix to achieve customer requirements and type approval legislation requirements, Euro 6e-bis represents a current development reality that demands immediate attention. Since EU6e is already established in Europe, those adapting advanced ICE efficiency will navigate the transition successfully while meeting regulatory requirements and market demands.

In related news, Scania releases new combustion and PHEV powertrains for buses and coaches

Kieran O’Regan, COO and co-founder, About:Energy, believes that virtual prototyping and digital modeling are the key to building better batteries, cells and systems.

The automotive industry faces immense challenges in its transition to electrification. Currently, physical prototyping and testing is used widely by the industry to determine critical performance factors regarding charging rates, thermal behavior, lifetime and safety. However, this is costly and time intensive and has bottlenecked innovation cycles.

Simulation has been used in the automotive industry for decades, particularly in chassis design, offering cost-effective alternatives to prototyping. Parameters such as the densities and mechanical properties were easier to measure so simulation was used effectively. However, this success is not easily replicated to battery pack designs. Obtaining the necessary data for accurate battery simulation is difficult, requiring extensive testing over months or even years to understand the characterization of cells to determine the thermal and electrical properties in various conditions.

Recently, Lucid Motors revealed it has invested years and £10m (US$12.65m) in testing in order to make optimal decisions in battery pack programs with the required data and simulation. Not every company can afford the cost and time needed before bringing profitable products to market. So a huge barrier exists for companies needing to effectively leverage simulation in battery management systems, thermal management or warranty design.

This is where virtual tools have emerged as a vital solution shaping the future of battery development. By providing advanced modeling and data analytics, these digital tools unlock major time and cost savings while accelerating the quality and competitiveness of battery-powered products.

At About:Energy our goal is to arm companies with the data they need to build better batteries and accelerate development timelines by reducing reliance on physical testing. Our software platform, The Voltt, aims to eliminate the need for costly in-house battery testing by giving engineering teams direct access to advanced battery intelligence. It integrates both virtual models and data from physical cell testing to give users unprecedented visibility into critical design choices across areas such as cell selection, thermal design and state-of-charge estimation.

The advantages of using digital tools also extend beyond automotive into any industry developing battery-powered devices. Industries such as consumer electronics, aerospace and energy storage can all benefit from virtual prototyping to enhance performance and reduce costs. Also, the inherent power of data is that the more data we have, the more accurate we can predict outcomes, which is another reason why digital tools will play a big role in the future of battery innovation.

As the industry continues to electrify beyond automotive and to smaller companies in industries such as maritime, e-mobility and aviation, demand for better, cheaper, safer batteries will continue to rise. Virtual prototyping is paving the way for faster innovation by giving companies the data and visibility they need to optimize designs and accelerate timelines.

Battery simulation is extensively used in the automotive sector and the future will likely see virtual and physical testing co-existing. Virtual tools fundamentally transform early-stage design and decision making, but implementation often comes with substantial cost and time investments.

Therefore, there’s an opportunity to enhance efficiency for large companies while also unlocking the technology for smaller companies that is currently out of reach. This shift could significantly increase battery innovation for the industry and accelerate electrification, making the journey smoother and more accessible for all players involved.

Sakor Technologies president Randal Beattie discusses the importance of driveline and component testing that is specifically designed for hybrid and electrical vehicles 

The key to reaping efficiency benefits
Over the past decade, most transportation markets, from automotive, to military, aircraft, and even space systems, have seen a tremendous surge in interest in hybrid and electric vehicle technology. To gain the promised efficiency benefits and green profile of these vehicles, it is important to conduct driveline and component testing during design and manufacturing that is specially adapted to the particular nature of hybrid and electric vehicles. 

Hybrid and electric drivetrains have several features that make testing them very different from the standard testing conducted on internal combustion-only (IC) systems. Hybrid and electric systems use regenerative braking (where braking actually generates power that is returned to and stored in the vehicle’s battery for later use). This typically requires the addition of fairly complex AC inverter technology, and often more complex transmissions. 

In addition, these vehicles often have several module control units (MCUs), essentially small onboard computers, which control the functions of such major subsystems as the engine, transmission and charging system, among others. To properly test these components, the test system needs to be able to communicate with one or more of these units via a high-speed in-vehicle network. This changing technology and increased complexity requires a testing system very different, and more complex, than those used in IC-only systems. 

The technology is out there to ensure proper testing and realization of the energy efficiency benefits promised by hybrid and electric vehicles. What’s more, the testing technology is itself energy efficient, reducing operations and maintenance costs and contributing to the vehicle’s overall environmental performance. 

Types of hybrid/EV driveline testing
Hybrid or electric driveline testing is conducted at several stages during the development of a vehicle, and each has an important role to play.

Engineering testing – design engineers need precise measurements
Accurate measurements are critical so design engineers can extract every bit of efficiency from their designs. Otherwise they will lose much of the advantage of using hybrid/electric technology. Most vehicles use three-phase AC motors driven by inverter technology, so sophisticated power analyzers are needed to properly measure three-phase AC power with a large amount of harmonic content. These test systems tend to be rather complex and are usually the most sophisticated, with many elements to be tested and coordinated.  

In-process and end-of-line testing – manufacturers verify performance and safety
Manufacturing end-of-line testing is usually performed to verify that no defects were introduced in the manufacturing process, and that the components will perform to specifications. Typical tests include operational validation, quick performance testing, as well as rigorous testing to validate that high-voltage electrical systems are properly isolated, and are therefore safe to use in vehicles. 

In-process testing may also be conducted to test partial assemblies along the production line. This improves manufacturing efficiency and significantly reduces the chance that faulty components will find their way into the finished product. 

Quality control testing – motor users look for defects in incoming product
Quality control (QC) testing is usually done on a percentage of the components to verify that that they perform over the specified range, and are relatively free of defects. For example, a forklift company may conduct QC testing on a shipment of imported electric motors that are scheduled to be placed inside their forklifts. They would use QC testing to verify that the shipment coming from their supplier performs as specified and will not experience high failure rates in the field. This type of test system is typically less complex, because it does not have to measure as many items, nor to the degree of accuracy, as those tested in engineering systems. 

Regenerative braking is the basis of improvement in fuel economy
Hybrid or electric vehicles use four-quadrant motor/inverter technology to either assist the engine (hybrid) or as the prime mover (electric vehicle).  Four quadrant means that the electric motor can control velocity or torque in either direction − the motor can accelerate, run, and decelerate forward or backward. 

During deceleration, the system uses regenerative braking, so the electric motor is used to slow the vehicle, and in the process becomes a generator, partially recapturing the energy of motion in the vehicle and restoring it to the battery. In hybrid systems, when stopping, slowing down or idling, the engine is typically shut off and not burning fuel. At the same time, the electric motor again becomes a generator, partially recouping energy and storing it back in the battery. The engine is switched back on when needed to keep the vehicle moving, or to accelerate. During this time, the electric motor assists in accelerating the vehicle, using some of the recaptured electrical energy to reduce the load on the engine, and therefore reduce fuel consumption. 

Using this recaptured power is the reason we can go longer between fill-ups and/or charges, leading to the improvements in fuel economy we are seeking. It is essential that the testing program used in designing and manufacturing the vehicles ensures that the powertrain is running efficiently and making the best use of this regenerative power. 

Testing systems for hybrid or electric vehicles
Testing hybrid and electric vehicles is worlds apart from traditional internal combustion engine testing, which typically measures speed, torque and a few temperatures, pressures and flows. Very precise control of speed and torque is typically not required in testing internal combustion engines, so dynamometers used for standard combustion engine testing (for example, water brake and eddy current) were never designed to handle the types of precision required by hybrid or electric powertrains, nor can they test the regenerative (motoring) modes of operation.

Modern hybrid/EV test systems must provide all of the functionality of traditional systems, with the added ability to test high-power regenerative electrical drives, high-voltage battery and charging systems, and communicate with any number of smart control modules (MCUs).

Electrical system testing
For many larger hybrid/electric drivetrains, there is a strong trend toward using higher voltage, higher efficiency drive systems. Going from the traditional 12/24V DC electric system to one using 240V AC will typically require one-eighth or less of the current to deliver the same power. Not only is this more efficient, but it also requires much smaller/lighter wiring and smaller components to transfer the energy, leading to smaller, lighter, more energy efficient vehicles. Many current designs operate at 800V or more, making the vehicles even more efficient. 

To conduct this type of testing, it is essential to use a four-quadrant motoring dynamometer, which can simulate/test all modes of operation in a hybrid or electric vehicle. The ability to drive or load in either direction is exactly what is needed to test a system that itself operates in this manner. A standard dynamometer is just not capable of testing the system during braking, when it is in regenerative mode. 

Creation of high-efficiency, AC-powered systems typically involves the use of three-phase, inverter-based technology to precisely control the electric motor(s) in the system. These systems tend to be very efficient, but also generate a great deal of harmonic distortion in the power output. So, in addition to the motoring dynamometer, a modern hybrid/EV test system typically includes a rather sophisticated three-phase power analyzer. This unit must be specifically designed to accurately measure high-power electrical values with a great deal of harmonic distortion present. 

To meet the need for a system that can fully test hybrid and electric vehicle drive systems, Sakor developed HybriDyne, a comprehensive test system for determining the performance, efficiency and durability of all aspects of hybrid drivetrain systems, including electrical assist (parallel hybrid), diesel electric (serial hybrid), and fully-electric vehicle systems. 

The HybriDyne integrates components of Sakor’s DynoLAB powertrain and electric motor data acquisition and control systems.  Coupled with one or more of its AccuDyne AC Motoring Dynamometers, and one or more precision power analyzers, the modular HybriDyne can test individual mechanical and/or electrical components, integrated sub-assemblies and complete drivetrains with a single system. 

High-voltage battery simulation and testing
A critical element of modern hybrid or electrical vehicles is the high-voltage battery and charging system. To accurately test a high voltage hybrid or electric drivetrain, you need to be able to provide precise, repeatable high-voltage DC power. Since battery performance changes over time depending upon their charge state, ambient conditions and age, they are typically not acceptable for powering the DC components of a hybrid/EV test system. To achieve repeatable results you need a reliable DC power source. A standard off-the-shelf power supply will not work, because it cannot absorb power from the regenerative system. In fact, a standard power supply used with a regenerative system may be damaged or destroyed. 

Sakor solved this problem by developing a solid state battery simulator/test system specifically to test high-voltage hybrid vehicle batteries and simulate these batteries in an electric drivetrain environment. 

At the heart of the system lies a high-efficiency, line-regenerative DC power source. During regenerative modes, absorbed power is regenerated back to the AC mains instead of being dissipated as waste heat, which is common practice among previous generation testing systems. This innovative method provides much greater power efficiency and measurably reduces overall operating costs. 

Coupled with the DynoLAB, the solid state battery simulator/tester accurately simulates the response of the high-voltage battery in real-world conditions. However, since it is not subject to a variable charge state, it provides repeatable results, test after test. This same unit, when operated as a battery tester, subjects the battery to the same charge/discharge profile as it would encounter in an actual vehicle on an actual road course. 

One of the advantages of using the AC dynamometer with a regenerative DC power source is that when the two are coupled together, the power absorbed by one unit can be re-circulated back to the other unit within the test system. This greatly reduces the power drawn from the AC mains (by as much as 85% to 90%), and therefore significantly reduces total cost of operation. This is an extremely energy efficient configuration, that can easily pay for itself, often many times over, during the life of the test system. Very low maintenance requirements also contribute significantly to lowering operating costs. 

Communication with control modules
Communication with individual control modules (MCUs) is another feature that has to be built in to testing systems for hybrid or electric vehicles. In the past, the engine was primarily controlled using the throttle and ignition. Now, engines have an engine control unit (ECU), the vehicle will likely have a separate MCU that controls the electric drive, and may have separate units for controlling the transmission and/or charging systems. These units typically communicate commands and/or data between themselves via a high-speed vehicle networks, such as CAN, LIN, FlexRay, etc. 

To properly test this complex drivetrain configuration, the test system must be able to communicate with these control units simultaneously and efficiently. The DynoLAB system was designed to integrate all of these separate units into a single, coordinated test platform.

There is great excitement in the automotive, heavy equipment, military and aerospace industries over the promise of improved environmental performance of hybrid and electrical vehicles. To achieve that promise, driveline testing programs must be adopted that meet the needs of this new and emerging technology. 

What is sustainable? It turns out the answer is quite complicated. Take, for example, a conversation I had with a supplier at the Reuters Automotive Europe conference in Munich. The company specializes in software to optimize materials and design selection in electrified powertrains, the idea being to find the most effective starting point for system design and detail optimization.

An interesting point was raised. The company’s technology looks not only at the properties of materials and parts but also at things like their carbon impact – vital for the creation of overall vehicle LCAs. Great, you may think, if sustainability is the target just pick the material with the lowest impact in its manufacturing stage. Not so fast: what if an alternative material has a more carbon-intensive manufacturing process but enables greater efficiency from a motor? Do the lifetime savings over a vehicle’s use cancel out the greater initial carbon cost? Then there are all the usual considerations of price and supply chain stability to factor in. See what I mean about things being complicated?

Fortunately, there are plenty of new tools to help engineers strike these balances and keep track of the myriad interactions that contribute to a vehicle’s lifetime emissions.

But what about once a car is in use? There is much debate (with plenty of shouting on all sides) about whether EVs really are the silver bullet for the decarbonization of transportation. They are undeniably a very efficient way to use renewable energy and are zero emission at the point of use. However, a BEV, when put next to a comparable ICE car, has a much greater level of embedded carbon from its manufacturing process.

Take a scenario I was pondering recently. Small city cars are arguably the best application of EVs because they produce no air pollution (beyond tire particulates) and less noise pollution. But is, for example, Fiat’s 500e (42kWh pack) a better bet for lifetime emissions than the company’s 1.0-liter mild-hybrid in a city setting? Usefully, both have been assessed under Green NCAP’s European LCA methodology.

A quick scan of the UK classifieds looking for 10-year-old cars (a reasonable life expectancy for a small car) of max 1.0 liter revealed just over 1,600 for sale. Of these, 50% had less than 100,000km on the clock. At this mileage, the 500e racks up 19.6 tons of CO₂ and the 1.0 gasoline 21.55 tons – a mere 1.95-ton difference. Over 20% of the cars had only covered around 60,000km, at which point the gasoline beats the electric by just over one ton of CO₂. Surely this is an argument for small-capacity PHEVs with a range of maybe 25km and a 15kWh battery pack if the goal is overall CO₂ emissions reduction?

Running the 500’s petite 1.0-liter ICE on E85 would knock a decent lump off the emissions and give a lower overall carbon cost. Or imagine if some of the R&D money being poured into BEV development were applied to upping the efficiency of small ICEs – the application of passive pre-chamber ignition systems detailed in the latest issue of APTi being one option. Could that swing the pendulum away from BEV in this particular case?

The point here is not to bash one approach in favor of another but merely to highlight that in the real world sustainability is complicated. Whether your remit is BEV, PHEV, ICE or H2, APTI is here to help unravel some of that complexity.

Porsche finally did it. For years the Cayman has played second fiddle to the 911, Stuttgart never endowing it with a powertrain that could threaten its icon. The Cayman GT4 RS changes that, thanks to the same 4.0-liter naturally aspirated flat-six as the 911 GT3 (and the 911 GT3 Cup race car) tucked amidships. Boy, does that engine define the car.

The raw figures promise something special: 500bhp and a redline of over 9,000rpm. It doesn’t disappoint. Add engine air inlets directly behind the driver’s and passengers’ ears, feeding individual throttle bodies, and the aural effect alone borders on feral.

The engine draws on Porsche’s motorsport experience. For example, the valvetrain relies on finger followers that do not require hydraulic lash compensation, improving reliability at high RPM. Meanwhile, the dry-sump oiling system uses no fewer than seven scavenging stages. This car will take as much track abuse as you can dish out. A caveat here: the Cayman was tested when temperatures were in minus figures with snow on the ground. Paired with Michelin Pilot Sport Cup 2 tires, those conditions meant opportunities to exercise the stratospheric redline were sparse. But when they arrived it was worth the wait (and sweaty palms).

The GT4 RS is an uncompromising beast, its interior spartan and, with the optional Weissach package, bedecked with carbon flourishes and a half-cage. The ride could best be described as robust, but the payoff is chassis feel in 4K. Given the opportunity to drive the GT4 RS back to back with a GTS 4.0, the laser sharp focus of the former was even more apparent.

Turn-in is almost telepathic and the singing-six allows the attitude of the chassis to be finessed with ease. Hard acceleration out of rough corners will get the rear skipping across the road surface but even then, the ESC and traction control – which provide enough freedom to keep things interesting – prevent anything getting out of hand. The chassis can be firmed up further via the Porsche Active Suspension Management (PASM) but in the UK at least, you’re not going to want to deploy this anywhere other than on a race track.

Could you drive this most hardcore of Caymans daily? Only the most committed would. But the GT4 RS is surely the ultimate iteration of the Cayman. It rewards with a driving experience that, in this synthetic age, delivers both visceral thrills and tack-sharp engagement for the driver.

With Porsche mooted to ditch ICE across the Boxster and Cayman range by mid-decade, it seems the company’s engineers were permitted one final hurrah with the GT4 RS. If this is the last of the gas-drinking Caymans, it is a fitting swan song and you would be hard pushed to find a more emotive drive at any price point.

Extreme fast-charging EV battery technology producer StoreDot is encouraging international automotive OEMs to adopt the mindset of a startup to bring advanced charging technologies to market faster.

The company is currently on track to mass produce its 100in5 silicon-dominant extreme fast-charging batteries in 2024, designed to provide a range of 100 miles after five minutes of charging. Despite the solution being capable of solving the issue of charging anxiety, StoreDot CEO Dr Doron Myersdorf is urging OEMs to re-evaluate their traditional technology introduction timelines to accelerate the adoption of these advanced technologies into new vehicles to offer increased benefits for customers, and a faster EV uptake.

More often than not, OEMs are locked into sequential prototyping and testing processes with timescales which fit the familiar long cycles of internal combustion engine (ICE) vehicle development. Despite this, vehicle manufacturers are capable of embracing new practices which use a more efficient mode of development to enable the latest technologies to make it to market faster through collaborations with scaleup-ready startups.

“We are working with many global OEMs and it’s clear that some are already changing their mindset to adopt advanced battery technologies faster,” explained Dr Doron Myersdorf, CEO, StoreDot. “But not every OEM behaves like this, and I believe the entire EV industry will benefit from accelerating its processes and timelines if we are going to collectively undertake the seismic shift to electrification that the world needs.

“With a typical five-year cycle to implement any new battery technology, we are encouraging global automotive manufacturers following traditional processes to adjust their methods and mindset to more agile business practices when evaluating and implementing innovative technologies. Testing of new technologies such as StoreDot’s Extreme Fast Charge – XFC – cells can be a strict, sequential, and laborious process that assumes a certain level of technology maturity. The upshot is that our game-changing batteries might not get into the hands of car buyers in a timely fashion. As charging anxiety is one of the main barriers to EV adoption, such conservative processes can have consequences for the entire battery and vehicle ecosystem and its ability to vastly and quickly improve the world in which we live.

“Of course, car makers must not ignore crucial elements such as safety and reliability testing, which are a given. But in my experience, some OEMs are still rigidly sticking to testing regimes that hinder the ability to take advantage of battery breakthroughs. Some parts of the automotive industry are currently being held back and will continue to be so unless we all adopt the agility of startup concurrent engineering practices.”

For more on electric powertrain technologies, click here.

It feels like a lifetime ago that Mazda introduced the Miller cycle in the Millenia. The Miller cycle, Mazda said, would revolutionize the way everyone built their combustion motors.

In the years that followed, the Millenia and its KJ-ZEM V6 Miller cycle engine were met with such an unenthusiastic response from customers that, by 2003, Mazda had run a tsurugi through the whole thing.

Mazda struggled to explain to journalists, much less its customers, what the oily, whizzing bits were doing, but even when it tried, its efforts focused on the wrong bit.

As a journalist of the era, I know that no one had preconceptions about the Miller cycle, but we got stuck on the supercharger. Superchargers, you see, were thought of as stuff the Yanks used in ’70s and ’80s hot rods and, as such, were a bit old hat. So that’s what most of the criticism was aimed at.
If they thought of the Miller cycle at all, the wider public got it confused it with the Atkinson cycle, which, as everyone knows, is a low-carbohydrate, high-protein fad combustion process popular in the early 2000s.

The other problem for journalists assessing the technology was that we couldn’t take Mazda’s claims to have unearthed The Next Big Thing in combustion power seriously, because not even Mazda did.

Mazda’s V6 engine department received an extra-large box of engine darts from Secret Santa in the mid ’90s and every engineer was hurling handfuls of them, willy-nilly, at an ‘approved program’ dartboard, then waiting for a promotion to the board. They brought out a 1.8-liter V6 that was so small you had to get it serviced at the jewelers. There was a 2.0-liter V6, a 2.3-liter Miller cycle V6, and a pair of 2.5-liter V6s, neither of which shared anything of value with the other. There was also a 3.0-liter and a 3.5-liter V6, just for giggles.

The company even had V8 and V12 atmo engines that were developed, validated and tooled up to production readiness before being shelved when the juicy profits of the luxury world never came.

It just felt to outsiders like Mazda was developing vee engines for a laugh (it had another dozen or so four-cylinder engines as well, plus commercial diesels), rather than with an aim of making money, and so it was proved, with Mazda going so close to drowning that Ford had to bail it out.
To Mazda’s great surprise, the company famous for one oddball, unique, expensive, weird-sounding engine technology couldn’t afford a second one. But the trouble wasn’t the Miller cycle technology. It was that the V6 Miller cycle got lost in the fog of Mazda V6s and no one followed them down the technology path.

So it was stuck on its own, Miller cycling away for a decade with a raspy, crunchy-sounding combustion process. There was no hive mind working on the problem like there is today.
Subaru finally thought it was a good idea and bunged it into the B5-TPH concept car in 2005, but didn’t put it into production. Saab came at the problem a different way, and came up with a variable-compression engine that no one put into production for many reasons.

But here we are in 2022, a full 20 years since Mazda killed the 2.3-liter Miller cycle V6, and Miller cycle engines have finally gone mainstream.

The main reason is that they’re a shortcut to cleaner emissions and every gram an engineer can shave off these days is worth approximately US$500 of heavy, consumer-oriented comfort that the product planning people can convince customers they need, thus neatly offsetting all that engineering work.

Volkswagen has Miller cycle engines in everything from the Golf to the Polo. BMW has just put one in the 740i limousine, after ironing out all the unsophisticated sounds Mazda stumbled across.
So Mazda has gone back to the Miller cycle, right? Err, no. Mazda has learned its lesson from going it alone on combustion technologies by, well, using another combustion process no one else uses.
At least Mazda is always interesting to watch.

Founded by entrepreneur William Li less than a decade ago, Nio has been making strides in the Chinese market with its expanding range of EVs – first SUVs and latterly saloons. Following an initial foray into the Norwegian market in 2021, the brand has now launched its full European expansion program, with the range-topping EL7 SUV and the ET7 and ET5 saloons available to buyers in the Netherlands, Germany and Denmark. Fei Shen joined Nio in 2015, when the company was still in its earliest startup days, signing on as employee number 274. Now the company has a workforce of over 15,000. His expertise lies in power systems, specifically very high-power, grid-level applications, and he currently holds the position of SVP at Nio Power, the arm of the company responsible for battery swapping, charging and infrastructure development. Automotive Powertrain Technology International spoke with Shen at Nio’s launch event in Berlin to gain an insight into the company’s unique approach to the EV charging conundrum.
Swappable advantage Prior to Nio’s European event, Shen undertook a 4,000km trip in one of the company’s ES8 SUVs, providing an opportunity to see Europe’s charging network up close. Overall, he says he was impressed with what he saw, even remarking that in terms of fast chargers, Europe was maybe ahead of China. However, Nio’s USP is its battery swapping approach, something that other manufacturers have toyed with but have failed to advance. Owners can drive to one of the company’s swap stations, of which there are currently around 1,150 in China, and in five minutes have their depleted battery swapped for a fresh unit via an automated process. Nio plans to have a further 1,000 of these stations operational in Europe by 2025. According to Shen, the initial decision to pursue battery swapping was simple. “We considered it the only means to make a user experience that is comparable with gasoline refueling.”

However, as the company matured, the perceived benefits of battery swapping clarified and various other advantages became apparent. “It is also about the implementation of ‘Battery as a Service’, which means we separate the battery cost from the vehicle,” he continues. Shen makes the point that over a vehicle’s lifetime, the cost of the battery and electricity used is not very different from that of ICE running costs – although this may change if energy prices continue to rise. The difference is that the ICE owner does not buy a 12- to 15-year supply of oil from the outset. “When EV users buy a car, they must spend additional money for the battery. So we considered that we should lower the initial price for the user to own an EV by separating the battery and vehicle.”

Another benefit Shen flags in favor of battery swapping is the potential for future upgrades. “Battery technology can be out of date very quickly and that is not great for the user experience. But if we separate the battery from the vehicle, then the user will always have the latest technology.” The final argument he brings forward is the efficiency that battery swapping offers at the system and grid level. “The battery swap station can charge batteries inside the station. At the same time, they can charge outside vehicles using chargers that are connected in parallel with the swap station and both the station and the chargers can share power from the local utility.”

The use rate of most chargers is only around 10%, whereas swap stations run at 30-50%, meaning the additional load of chargers on the same site can be easily accommodated. The chargers are also able to run from the batteries stored in the stations, which in turn can be charged using off-peak electricity. The overall result is a more balanced load on the local electricity grid. “The swap station is a large-capacity storage system; with 30 batteries you have 1.3MWh. We can also charge when prices are lower, or when there is an excess of clean energy – solar or wind – in the power system.”

Big batteries One of the most appealing features of Nio’s battery swap system is that its batteries, regardless of capacity, share the same footprint and are designed to be backward compatible. Currently its highest capacity offering is 100kWh. A 150kWh unit that is under development was due to hit the market in 2022 but its release has been delayed. Impressively, though the new battery will give a 50% increase in capacity, the weight of the pack has grown only marginally compared with the 100kWh variant. “We have defined the same size, a very, very similar shape and almost the same weight for the battery. To increase the battery capacity the energy density was increased, but with the new technology the weight is not increased.” He points out that the large pack will only be relevant to a small proportion of customers, and the company expects most will still opt for the standard range offering, taking advantage of being able to make a short-term upgrade to larger capacities as their needs dictate.

“Most of the time, users only drive their vehicles in cities, and most [in the China market] choose the 75kWh battery.” Notably, Shen adds that there have been multiple requests from users for a smaller 50kWh pack to reduce costs further, but this is not something the company is developing. “It’s very challenging and I think the schedule is slightly behind plan,” admits Shen. “We are still working on the 150kWh battery. We originally planned to deliver it at the end of this year but now it is scheduled for release in China in Q1 2023.” He adds that the battery will eventually be rolled out in Europe once it meets the required standards. “It is quite an innovative technology and increasing the energy density of the battery in the same package size is a bigger challenge than we expected.”

The official company line is that it is working with long-term battery partner CATL on the development of this pack. However, a relative newcomer to the battery market in China, WeLion, stated earlier this year that it had been developing a semi-solid-state chemistry for Nio to use in the pack. Whichever turns out to be the final solution, if Nio can bring a 150kWh battery to market by 2023 it will be a major milestone for the industry and ahead of most of its competitors. While Nio is still climbing the ladder to compete with established manufacturers, its lack of legacy infrastructure burden and what appears to be a genuinely fresh approach to vehicle design, development and manufacture, not to mention management structure, appear to make it well placed to capitalize on the EV transition. Confidence is certainly high, with Shen concluding, “The reason I think we can do these kinds of things much better than other companies is because we do it as one team.”