A unique collaboration for the development of the next generation electric transmission fluid

Influence of lubricant on electrical drive unit

In the rapidly growing Chinese EV market, for a new EV product to stand out, it needs to provide premier performance in range, NVH and reliability under all operating conditions, regardless of drive cycle (city, rural or highway) in climate extremes.

Weiyi Wang, Engineering Manager, Li-Auto
Guodong Liu, Insulation and Lubricant Engineer, Li-Auto
Lucy Hu, R&D Group Leader, Driveline, Afton Chemical Corporation
Jon Horner, Senior R&D Engineering Specialist, Afton Chemical Corporation
Wenjun Liu, Senior CTS Specialist, Afton Chemical Corporation
Yun Zhang, Senior OEM relationship Manager, Afton Chemical Corporation

To make an EV successful, the electrical drive needs to have the highest efficiency while enduring high power density to provide outstanding reliability. To achieve this, the lubricant plays a crucial role as it is the means to remove heat from the motor while providing lubrication and protection for gears and bearings. The list below displays examples of how a lubricant can influence an EV’s drivetrain performance.

Scuffing, Pitting and Wear Protection – Poor lubrication is the primary failure mechanism for all of these phenomena. When a lubricant fails to provide proper extreme pressure or scuffing and anti-wear protection during high contact pressures and high sliding speeds, the gears and bearings can rapidly fail.

Coefficient of Friction – The gear meshing and bearing frictional losses account for 30-40% of total power loss in EDU, especially when experiencing higher power demands. All gears and bearings are lubricated with the electric transmission fluid (ETF), so lowering the coefficient of friction is one of the most effective ways to improve a drivetrain’s efficiency.

Electrical Properties – Breakdown voltage, resistivity, and permittivity can influence the electrical induced bearing damage (EIBD) behavior, which is a unique and challenging problem for all inverter driven motors due to common mode dV/dT events and circulating currents.

Understanding that the appropriately formulated ETF technology is the key to promote efficiency, durability and reliability of an EDU, Li-Auto has engaged with Afton Chemical Company to develop a customized ETF to best suit the Li-Auto in-house-designed drive unit.

Li-Auto’s Methodology on the customized ETF’s development

The next generation ETF, Advanced Performance Fluid 1.0 (APF1.0), was designed and developed specifically for Li-Auto’s next generation, in-house designed drive unit, Scalable Power Drive (SPD) (see Figure 1). This is the main drive platform for both REV and BEV models.

SPD is an 800V electrical drive unit platform. The inverter, motor and gearbox are integrated as one whole assembly, but its peak power and torque could be tuned from 200~300kW, 3500~5000Nm by adjusting power modules, stator & rotor, or geartrain as it is a modular designed drive unit. It enables SPD to suit various car models. Apart from that, SPD has boost charging function, which significantly reduces charging time but meanwhile much more heat is generated from the rotor. The system poses great challenge on cooling and lubrication, and APF1.0 needs to have great heat dissipation and hardware protection performance. On top of that, Li-Auto has focused on how this directly contributes to the vehicle range and battery cell cost, which ultimately influences the overall vehicle performance.

The ETF design is an optimum combination of chemical additives and base oil technology to deliver balanced performance. If the balance is not adhered to, the desired level of performance in the drive unit can be compromised.

The primary design target for the APF1.0 development was efficiency, while providing adequate hardware protection, especially under low lambda ratios. To improve efficiency, a geartrain power loss model was developed to calculate the contribution from sliding and rolling losses and churning losses (gears and bearings) to better guide the lubricant formula design. During the modeling work, it was found that different hardware configurations yield different power loss contributions.For example, churning loss is greatly reduced in a geartrain with intermediate shaft placed on top (no contact with sump oil, as illustrated in Figure 2) compared to that placed at the bottom (partially submerged in oil sump) and rolling frictional loss could be greatly reduced with ball bearings versus tapered-roller bearings.

*Geartrain configuration of above figure:
BTTO – Ball bearings on input shaft, Tapered roller bearings on intermediate and output shaft, intermediate shaft on top with churning from output gear only
BTTIO – Ball bearings on input shaft, Tapered roller bearings on intermediate and output shaft, intermediate shaft on bottom with churning from both intermediate gear and output gear
BBTO – Ball bearings on input and intermediate shaft, Tapered roller bearings on output shaft, intermediate shaft on top with churning from output gear only
*Power loss calculation models:
Gear mesh & churning loss is calculated per ISO14179-1;
Bearing loss is calculated per SKF’s public bearing loss empirical model

The same to hardware protection. For example, pitting life reduces exponentially as contact stress in-creases for gears and bearings. If the hardware design puts the contact stress near the limit, it will be required to have an ETF that has ultra-high-performance regarding pitting and scuffing. In this scenario a higher viscosity would be preferred to ensure oil film is sufficient. On the contrary, if the drivetrain is under lower stress level, a lower viscosity fluid could be applied to provide the greatest vehicle range.

Based on the aforementioned performance factors, Li-Auto decided that the APF1.0 design had to be customized to obtain the best performance with the SPD hardware. An off-the-shelf product will not provide the ultimate performance. Li-Auto selected Afton Chemical as cooperation partner as Afton fully understands Li-Auto’s technological capability and provides a new formulation that meets the specified requirements, providing both range extension and hardware durability.

In this cooperation project, both parties agreed that as OEM, Li-Auto’s role is to provide clear and specific evaluation methods for the lubricant based on Li-Auto’s hardware design; and as the lubricant expert, Afton’s role is to design and develop formulas that could meet Li-Auto’s requirement. During this process, it was found that the conventional lubricant evaluation methods such as FZG (spur gears) and FE8 (cylindrical roller) do not appropriately evaluate APF1.0 as related to the end application utilizing helical gears, ball and tapered roller bearings. Thus, we designed our own evaluation methods in terms of pitting prevention, friction optimization and churning loss based on our hardware design and actual operating conditions from fleet statistic data.

Performance evaluation of APF1.0

The efficiency performance of APF1.0 was evaluated by comparing it with the previous generation fluid on the same dyno and the same drive unit (a selected SPD drive unit, with baseline efficiency of 91% – CLTC drive cycle at 40°C). APF1.0 provides a 0.3% efficiency increase per CLTC drive cycle at 40°C oil sump temperature; 1.1% increase per CLTC drive cycle at -7°C oil sump temperature; 0.5% increase under 120kph highway cruising condition at 40°C. It showed significant efficiency increase at both normal and cold temperatures, both city-road and highway conditions.

Fig. 4 Efficiency gain chart of APF1.0

On the reliability side, we performed the geartrain endurance test, high temperature high speed test, power temperature cycling endurance (PTCE) equivalent to the EV life of 300,000 kilometers, covering driving intensity of 99.7% of fleet drivers. No failure was detected after any of the tests.

Before performing efficiency and endurance tests on full drive unit level, we conducted a series of lubricants screens to ensure valuable dyno stand resources were maximized for candidates. We set coefficient of friction reduction targets for the lubricant at multiple operating conditions based on the power loss simulation model and set clear requirements on the lubricant’s hardware protections. Only those formulas that met all the requirements would be selected to the drive unit level test phase.

For friction evaluations at lubricant level, MTM was used to determine the friction performance of the fluids. The friction performance was compared to the reference at different loads, entrainment speeds, slide-to-roll ratios and bulk oil temperatures. The operating conditions are derived from the drivetrain’s actual operating conditions and allows an appropriate insight as to how the fluid can influence overall efficiency as related to friction reduction.

On the hardware protection lubricant level test side, since APF1.0 is a low viscosity lubricant used in a high power density, high torque drivetrain, we are most concerned about a fluid’s pitting and wear protection capability. For pitting, we used MPR test equipment for evaluation. We specified contact stress, sliding speed, entrainment speed and run time based on one of the most aggressive drivers’ driving profiles collected from fleet data. The reference fluid pitted after 38.77 million cycles (43.7hrs) but APF1.0 was able to complete 87.83 million cycles (99hrs) without pitting.

Projection of ETF trend

We believe the items listed below will be the future of ETF development from an OEM standpoint.

Efficiency is always the first priority, as it is the key to reduce the overall cost of the vehicle and resolve EV range anxiety. New combinations of additives and base oils are currently underway to reduce coefficient at thin film conditions, and improve durability while improving EDU efficiency at lighter load duty cycles. In the future, base oil and additives with new molecular structures could potentially further bring friction down.

Viscosity should be carefully selected based on hardware protection needs. Low viscosity does not always provide higher efficiency gains in an EDU. An ETF with properly selected viscosity could allow more operating conditions to fall into the elastohydrodynamic regime (which gives lowest coefficient of friction). To achieve such, the OEM needs to build capability to perform drivetrain power loss analysis and component loss simulations with input from gear, bearing and lubricant suppliers.

EIBD is a unique phenomenon and challenging topic for BEV and REV drivetrain. Lubricant properties such as breakdown voltage, resistivity, and permittivity could result in different EIBD performance theoretically, and it has been observed from tests that different lubricants do yield different discharge event frequency and severity. It is valuable for the lubricant and powertrain industry to make further study on ETF’s influence to EIBD and provide formula that mitigates EIBD risk in the end.

Li-Auto highly encourages all of its partners in the drivetrain supply chain to join in this effort to make the next significant steps to improve EVs further in cost and performance.

JJE advances differential locker technology JJE differential locker driven by DirectFluxTM electromagnetic clutches

Differential locker locks up differential to ensure torque output on vehicle’s wheel under low traction conditions. the axles together to provide 100% of available torque to the wheel with traction. At 2022 CTI US, JJE debuted its mono-stable and bi-stable DirectFlux differential locker (eLocker). Now this eLocker has been equipped by mid- and full-size SUVs, pickup trucks, and off-road vehicles. JJE eLocker features compact size, high torque, and high engagement speed. JJE has achieved maximum 18,000Nm locking torque in JJE’s 2-speed electric beam axle. Depending on vehicle requirement, JJE’s eLocker can be bi-stable, which is fail-safe (prevent sudden locker release and loss of traction); or can be mono-stable to achieve “default to open” function.

Ping Yu, CEO, Chief Engineer, Founder, Jing-Jin Electric
Dr Yang Cao, Transmission Clutch Team Manager, Jing-Jin Electric

DirectFluxTM electromagnetic clutch makes locking faster and safer

DirectFluxTM electromagnetic technology clutch is used to drive the locker. The clutch uses direct magnetic force, or magneticflux in the same direction as the magnetic force. JJE created unique magnetic circuit that greatly reduces flux leakage, hence utilizes the magnetic flux to generate force more effectively, generating higher electromagnetic force than conventional reluctance clutches. With the DirectFluxTM electromagnetic technology clutch, eLocker can be designed as mono-stable or bi-stable based on vehicle requirement. A mono-stable eLocker is locked by magnetic force generated by current, and is unlocked by spring force when the current is turned off. A bi-stable eLocker will only change its state when there’s an affirmative current command, which is only a pulse; otherwise, it will hold its state.

Normally, bi-stable differential locker provides higher safety level, as it won’t change state in the event of loss of control. This fail-safe feature can prevent sudden locker release due to control failure. This security enhancement is valuable for rear axle, or the “main drive axle”, for conditions such as claiming steep rock trail or pulling heavy boat out of water on slippery ramp. While for front steerable axle, mono-stable differential locker is sometimes preferred as it will default to open position in the event of control failure, which unlocks the front differential to allow easier steering at higher speed.

No speed limit, no drag loss

Conventional locking differential must limit vehicle speed very low for engagement, and also limit vehicle’s running speed after engagement. “The locker engagement should not be maintained greater than 30kph”, or “the locker only can be engaged when vehicle speed is below 5kph”. The operating speed is limited by the rotational friction between differential case and electromagnetic coil case during locker’s engagment. And the conventional locker can only be mono-stable.

JJE’s eLocker is driven by DirectFluxTM electromagnetic clutch, which has no contact or friction between moving plate and coil assembly during engagement and disengagement. Therefore, there is no mechanical wear, no drag loss, no heat generation. Therefore, JJE eLoker does not limit speed for engagement or operation.

Wide application

Differential locker is indispensable in off-road vehicles, and other high capability vehicles such as heavy duty pick-up trucks JJE’s eLocker has been used in several independent axle 3-in-1 drive units, with output torque ranging from 3000Nm to 6,000Nm. The differential locker is also adopted in JJE’s 18,000Nm electric beam axle. JJE eLocker does not limit operating speed, which enhances these vehicles’ capabilities when both locking and speed are needed, e.g., driving through sand or mud.

JJE eLocker for back-to-back dual motor drive

Back-to-back dual motor e-drive does not require a differential, but some vehicles do require a locker that mechanically locks up left and right wheels. JJE’s electromagnetic clutch is suited for such locker function. JJE has two back-to-back dual motor drive units – coaxial planetary and offset layshaft – and both drive units use bi-stable electromagnetic clutch as locker.

Fig. 4 JJE’s eLocker for back-to-back dual motor drive unit

JJE eLocker & eDisconnect combo system

JJE eLocker can also be integrated with JJE eDisconnect, which becomes a compact disconnect & locker combo. This combo is most valued for secondary drive axle, where disconnect is used for changing configuration between 4×4 and 4×2, and locker is used for traction assurance. As example, a 4×4 off-road SUV needs such flexibility.

The eLocker-eDisconnect Combo packages nearly the same as JJE’s single eLocker, thanks to the deeply integrated mechanical design and very its compact electromagnetic elements. This new Combo product will be launched in a high-end off-road SUV in 2025.

Fig. 5 eLocker & eDisconnect solution for high-end off-road SUV

eDrive application rapidly expands and now reaches almost all market segments. Users accept no compromise in vehicle’s capability, and even expect more from eDrive than ICE. JJE eLocker, eDisconnect and the Combo are designed to meet such high market expectations, and will continue to push out the envelope of technology.

Electric First – Where Possible

In 2024, the electrification process in Europe stuttered – but as the discussions at the 27th CTI Symposium made clear, it is not about to stop. Other interesting topics in Berlin included insights on India as a future market or advances in digitalization and artificial intelligence. And the Software-Defined Vehicle is about to become more than a buzzword.

2024 had several surprises for the automotive industry, particularly the lack of European sales figures for all-electric passenger BEVs. That does not signal the demise of electromobility; after all, no sector ever experiences uninterrupted growth. But it has revived the topic of plug-in hybrids, or more precisely, a new type of range extender known as EREVs (Range Extended Electric Vehicles) or REEVs. These highly electrified serial or serial-parallel hybrids are standard fare in China today.

Naturally, these developments also played a role at the CTI Symposium Berlin, which took place on December 3 and 4, 2024, at the usual venue, Estrel Hotel in Neukölln, Berlin. Hosted by Prof. Malte Jaensch, Chair of Sustainable Mobile Powertrains at the Technical University of Munich, there were three key themes in the plenary lectures and panel discussions: How are markets and regulations developing in Europe and future markets such as India? Which drive concepts are gaining ground in passenger cars and commercial vehicles? Finally, a topic playing an increasingly important role: digitalization and new opportunities based on artificial intelligence.

India – the next big market?

For some observers, India is an upcoming market with great potential. In his lecture “Indian Automotive Market – Trends and Regulation Insights”, Amit Gupta, CEO of Hero Motors, provided some statistics: India is the world’s fifth largest market economy, with a population of 1.43 billion. With a median age of just 29.5 years (compared to 42.5 in Europe), India is a very young country with vast potential for future car buyers. Gupta divided developments over the last few decades into five phases: Before 1982, there were just five car manufacturers, all Indian companies. From 1983 to 1991, Maruti dominated the market. From 1991 to 2010, a good 20 companies emerged, offering mainly small cars. By 2020, premium vehicles and (like everywhere else in the world) SUVs increasingly entered the mix. Then, after 2020, electrification gained momentum in India, and exports grew. Hero Motors itself supplies a range of drive components. Gupta said electrification in India had gained momentum recently, rising to around 1.7 million electric vehicles in 2024 from around 146,000 in 2010. However, more than half of these were two-wheelers. Incidentally, this growth was supported by a program called „Faster Adoption and Manufacturing of Electric Vehicles“ (FAME II), which expired in March 2024.

Is regulation harmful or valuable?

That leads to the question of how far regulations can assist in introducing new technology – or as the first panel discussion put it: „Does Regulation Kill Innovation?” The participants were Dr. Peter Mock, Managing Director of ICCT Europe, Dr. Manfred Schuckert, Head of Regulatory Strategy & Int. Hydrogen Strategy, Daimler Truck AG, and Hui Zhang, Managing Director NIO Europe. The moderator was Ulrich Walter.

Manfred Schuckert called for regulations that are properly thought through. Specifically, he criticized the tank-to-wheel model still used in Europe, which ignores all other CO₂ emissions during the product cycle. By this logic, he noted ironically, even when hydrogen is burned – a process that is CO₂-neutral – the CO₂ from the intake air gets measured at the exhaust. Schuckert also pointed out that commercial vehicle manufacturers, particularly, depend on the energy infrastructure. Drawing politicians’ attention to requirements such as the number of charging stations needed for electric truck fleets, he said, was a complex and ongoing task. He also questioned whether political regulations are always implemented at the desired speed. He said that the EU Commission is often unwilling to follow industry recommendations; things were very different in China.

Peter Mock, in contrast, came out in favor of legal regulations. He also opposed that relaxing European regulations was justified if emissions were shifted to other world regions. Asked whether it might now be time to make up with the industry after Dieselgate, he replied: „No, this completely destroyed the relationship, basically because it was just one scandal too many.“ Mock said the entire automotive industry had lied for years and was astonished that the industry now „dared“ to appeal to the government once again, arguing that the jobs it provided were crucial.

In addition to his role as a representative of carmaker Nio, Hui Zhang provided some interesting insights into how a Chinese expert perceives matters. He said the EU was over-regulated, an opinion he backed up with corresponding statements made by Emmanuel Macron. Zhang said every innovation needs space for competition first; regulations should only be the next step. In other words: „Be open-minded before you start regulating.“ Zhang also said that normal consumers need incentives. They were cost-driven, and in this sense, „the user is always right“. Energy costs in Germany were far too high, and it was only natural for users to react.

Securing raw materials and energy sources

Regarding energy and raw materials, Karin Pittel, ifo Institute, offered extensive insights and several recommendations in her lecture: „Building a Sustainable Mobility Future: Challenges from Energy and Resource Markets“. She said the availability of lithium, and even more so of cobalt, was critical, especially since Germany depended 100 percent on imports. Otherwise, fossil fuels such as oil, gas, and coal would still be around for a long time, and prices were likely to fall. This, in turn, would make electric cars less attractive to buyers. The switch to hydrogen is not that easy either, said Pittel, as production and consumption sites are scattered around the globe. She closed on the topic of supply chain disruption, saying this hit Germany harder than other Western countries during Covid-19, cutting productivity there by 8 percent. So, what can we do in the face of all these dependencies? Pittel believes we must diversify more, improve cooperation in Europe, and closely examine how we view conflicts between economic and humanitarian objectives. We need to strengthen our information base to identify risks early – and not forget the need to “really do something”, which typically can happen when the alertness after a crisis goes down.

Are swappable batteries coming?

In addition to participating in the first panel discussion, Hui Zhang also lectured on „Nio’s Power Strategy for Europe – Combining Mobility and Energy Transition“. Nio was founded in China in 2014 and has around 1,000 employees in Europe, with sites in Germany in Berlin, Brandenburg, and Munich. Nio currently operates 2,500 Power Swap Stations worldwide, with 58 in Europe at the end of 2024. So, what are the advantages of swappable batteries? According to Zhang, they are as fast as refueling – even fast charging doesn’t come close. And with automatic swapping, you don’t even have to leave your car. Vehicle prices are less dependent on the battery, and the batteries will be checked every time you swap. You can even swap to a different-size battery if needed. When a delegate asked whether a swap system would not require more batteries, Zhang cited this greater flexibility as a counter-argument. As the lecture title made clear, Zhang also sees exchange batteries as part of the energy infrastructure, saying they can be part of a grid while stored at the swap stations. It will be interesting to see whether Nio succeeds in the European market. By the way, drivers can charge their swap battery EVs directly like any other EV.

BEVs and supplementary hydrogen for long hauls

As Christian Krajewski, Daimler Truck AG, showed in his lecture „Daimler Truck on the Way to CO₂ Neutrality”, Daimler Truck’s primary strategy for its commercial vehicles is BEV, with fuel cell for long-haul applications too. As the speaker pointed out, the EU requires commercial vehicles to emit 15 percent less CO₂ from 2025 on and 45 percent less by 2030, compared to 2019. The Daimler Truck portfolio includes the eActros 300/400 models for medium-range work, the eActros 600, and the GenH2 Truck with fuel cell. In his lecture, Krajewski focussed on the eActros 600. Its range is 500 km from a 621 kWh battery, and it can charge from 20 to 80% in less than half an hour using megawatt charging. Efficiency is always 95% or higher. Instead of a central drive, Daimler has opted for an eAxle, which is more compact and efficient. At 750 V, the drive delivers 600 kWp and 400 kW of continuous power. Inverter-to-wheel efficiency is 92%, while wheel torque tops 40,000 Nm. The four-speed gearbox is interesting, with steps 1/2 and 3/4 implemented as powershifts. Krajewski said Daimler still saw fuel cells as suitable for long-haul transportation. He is not in favor of H2 combustion engines, given the load profile of heavy trucks meant that fuel cells would use hydrogen more efficiently.

Electrification keeps the ICE running

Do combustion engines still have a future? That question was highly topical, given the modest BEV sales figures in 2024. Under the heading „Back from the Dead? ICE in Passenger Vehicles“, moderator Ulrich Walter discussed the issue with Dr. Norbert Alt, FEV, Prof. Maximilian Brauer from the TU Berlin, Dr. Tobias Block from the eFuel Alliance, and Prof. Markus Lienkamp from the TU Munich.

As head strategist of the eFuel Alliance, it was no surprise that Tobias Block sees a future for combustion engines. But he also spoke about the challenges of offering eFuels in sufficient quantities in the EU. He said there won’t be many investments if the legislation only focuses on niche markets. For example, in 2030, there would be only 0.7 % eFuels mandates for aviation and only 1 % for the maritime sector. Another example is that eFuel makers had to produce eFuels using only renewable electricity from installations not older than 36 months. BEVs otherwise were allowed to use fossil-based electricity. Block also cited a joint study with Porsche Consulting. Based on tracking data from 430 projects, the study predicts an annual worldwide production volume of 11 billion liters of eFuels in 2030. Block believes consumers should have the opportunity to run combustion engines on CO₂-neutral fuels if they wish.

Norbert Alt spoke passionately in favor of electrification. Technically, photovoltaic charging power could be produced for 10 cents/kWh in Germany, allowing people to opt for BEVs immediately. However, Germany needed to speed up development activities. Otherwise, „the Chinese will end up doing everything“. Interestingly, Alt pointed out that most development work on combustion engines now also takes place in China, saying Germany should not yield its position in that field either. Looking ahead, he sees combustion engines primarily as part of REEVs, or range extended electric vehicles. These were a major trend in China, and they would also be coming to Europe. REEVs were basically variants of electric platforms with a long electric range, designed as serial or serial-parallel hybrids. Technology-wise, serial hybrids were a simple solution – and with modern inverters, conversion losses no longer played a significant role.

Markus Lienkamp said hydrogen was not an option for him, as it was simply not affordable. Based on a realistic energy mix, the Technical University of Munich had calculated that due to the battery’s CO₂ burden, BEVs made less sense than rental cars for annual mileages under 5,000 km. Specific low-mileage applications, such as fire trucks, could run on eFuels. However, diesel might be preferable in terms of overall environmental impact. In principle, despite the current slump, the long-term trend was for BEVs. Lienkamp advocated using a push-pull strategy to nudge consumers in that direction.

Taking up the discussion’s title question, Maximilian Brauer began by saying that hybrids, and hence combustion engines, were actually experiencing steady growth, not a revival. Like his fellow participants, he expects all-electric drives to dominate in the future. Still, he also believes in creating a level playing field for eFuels. In terms of technology, Brauer says German manufacturers definitely do not lag behind China. His take on consumer behavior in Germany was succinct: „As long as BEVs stay expensive, people will stick with combustion engines.“

Summing up, all the participants agreed on two points: Electrification comes first; combustion engines will still be around, albeit mainly as servants in highly electrified vehicle platforms.

AI agents assist drivers

‘Digitalization and AI methods’ is a topic of growing importance at the CTI Symposium. There were two plenary lectures on the subject – one from Sabine Calvo, Renault, and the other from William Wei, FTP Automotive.

William Wei focused on how AI ‘agents’ can help drivers operate their vehicles more efficiently. Up to now, the vehicle code has been static, making functions and their operation fixed and rigid. The future belonged to ‘agents’ powered by AI and Large Language Models (LLM) with functionality that was neither static nor fixed but defined through end-to-end training. This method trains systems as a whole, not as separate functional modules. Wei spoke of the ‘brain’ of the car, saying drivers could, for example, operate their vehicle by communicating with it freely. In the next era of the „software defined vehicle,“ Wei foresees an AI infrastructure that is integrated down to chip level – a form of in-car Edge AI Computing. Functional safety, however, (for example during autonomous driving) was always rule-based, and hence required its own safety layer in the vehicle. This layer would sit as a safeguard between the vehicle sensors and the LLMs and agent level.

Digital Twin in all development stages

Dr. Sabine Calvo is Vice President Engineering Performance, Validations & Digital Transformation at the Renault Group. She described „How Digital Transformation will Support Breakthrough in Time-To-Market Acceleration and Cost Reduction” using various examples. Renault now needed just two years to develop a car. Digital Twin played a significant role in practically all vehicle functions. As a result, validation costs have been halved since 2019, she said. Calvo named three steps in digital simulation: The vehicle, the embedded systems, and immersive simulation. As a vehicle example, she used a crash test with a digital twin, showing almost no difference between simulation and reality. Other fields included aerodynamics, acoustics, strength, and thermal management. Examples of embedded systems include ADAS, systems & software, and energy management. Here, Calvo noted that virtual ADAS covered several million kilometers in 2024. Immersive simulation is used to simulate the design of car interiors – again, with hardly any visible differences. Renault also operates a closed driving simulator that allows drivers to experience the properties of the digital twin. Finally, Calvo touched briefly on AI, saying it was already used to make pre-development design suggestions. This led to prototypes with higher functional maturity at lower costs for physical tests.

Digital, Circular, Electric

In his lecture „Innovation as Driver of the Future,” Rudolf Bencker, BMW, named three core focus areas: „Digital, Circular and Electric.“ In digitalization, BMW backs features including panoramic in-vehicle displays, in-car gaming, mixed reality or the „Car Expert” – an AI-like in-car assistant based on large language models (LLM). At BMW, Circular Economy includes the use of new materials, circular manufacturing, and more efficient use of resources in general. While BMW is known for its open-minded approach to drive technology, the manufacturer’s BEVs are remarkably successful – the company sold its one-millionth BEV in 2024. BMW also continues to pursue plug-in hybrids, combustion engines, and fuel cell drives such as the one in the iX5. This comprises a 170 kW buffer battery, the 295 kW electric motor, the 125 kW fuel cells, and hydrogen tanks with a capacity of 6 kg. Even for passenger cars, Bencker sees hydrogen as a building block that can help to diversify energy infrastructures in regions with few charging options or when high-speed refueling is essential.

Electrification, AI and new markets

Of course, the animated discussion about the pros and cons of various drive concepts at the 27th CTI Symposium was not the first of its kind. In his summary, chair Prof. Malte Jaensch shared his opinion of BEVs, saying the right strategy is quite simple: Where possible, electrify. Where not, use hydrogen if possible or e-fuels if not. For passenger cars at least, this was a very simple rule of thumb. Jaensch was equally clear on AI, saying it may still be primarily about in-vehicle operation, as William Wei showed in his lecture, but AI in cars would develop rapidly. Today, AI helped us open windows; tomorrow it would help to improve autonomous driving; and after that, who knows? Jaensch followed up with two more insights: First, we should bear in mind that India is currently the only large market with strong growth potential. Second, a reminder to politicians: Dependable regulation is at least as important as „correct“ regulation.

Given the recent political upheavals, this will likely be a challenging task in 2025 for the industry. The next opportunity to discuss future opportunities and technologies will be at the CTI Symposium Novi

in Michigan (May 13 and 14, 2025). There will also be special events for women in automotive, students, young professionals, and startups in the powertrain industry. We warmly invite you to participate as a speaker, delegate or exhibitor!