Posted on 4th February 2026

DI (FH) Wilhelm Vallant, Product and Business Development Manager Transmission & E-axle, AVL List GmbH

The automotive sector is experiencing a profound transformation towards electrification, motivated by the dual objectives of mitigating greenhouse gas emissions and ensuring uncompromised vehicle performance. Original Equipment Manufacturers (OEMs) are increasingly challenged to meet rigorous sustainability and cost-efficiency benchmarks. In response, AVL introduces a forward thinking and validated solution that establishes new standards in electric drive unit (EDU) efficiency, lifecycle CO2 emissions reduction, and system integration.

This article details the development and empirical validation of a high-efficiency EDU system that achieves an average cycle efficiency exceeding 94 % under the Worldwide Harmonized Light Vehicles Test Procedure (WLTP) as well as the China Light-Duty Vehicle Test Cycle (CLTC) and maintains vehicle energy consumption below 10 kWh per 100 km. The discussion further encompasses the technological advancements and sustainability frameworks that underpin these accomplishments.

EDU Architecture and Operational Strategy

At the core of a demonstrator vehicle developed by AVL as part of an R&D project lies a dual-motor EDU configuration consisting of:

• Two Permanent Magnet Synchronous Machines (PMSMs)
• A compact, single-stage spur-gear transmission with double helical gears
• Compact final drive with integrated planetary gear differential
• A dual Silicon Carbide (SiC) inverter system
• Oil catch tank to decrease the oil level during operation

o meet the ambitious energy consumption and efficiency goals, an innovation-driven development process was implemented, enabling the early-stage comparison of a wide range of technologies. By applying advanced simulation methods, numerous potential solutions can be evaluated early on in terms of their alignment with the project objectives. Key measures include component technology selection, architectural studies to balance performance and losses and system simulation using AVL’s proprietary development toolchain, the Powertrain System Optimizer (PSO). Step by step, the number of possible variants is reduced by selecting the most promising solutions, while the level of simulation detail is progressively increased. Once only a few options remain, detailed component optimization and initial control strategy refinement are carried out in the final development phase. FIGURE 1 illustrates the AVL PSO methodology.

Figure 1: AVL Powertrain System Optimizer Workflow

The selection of transmission, electric motor and inverter technologies was guided by cost reduction and sustainability, with a focus on intelligent integration, minimizing drag losses and using efficient materials. Achieving maximum efficiency in the EDU architecture was essential to reaching a WLTP cycle efficiency of more than 94 %, and a dual-motor concept proved to be the most effective solution. The main motor was designed for efficient continuous operation, while the secondary motor supports boosting and recuperation. This secondary motor, which can be decoupled via a dog clutch, was specifically optimized for its intended use and the load points defined by the operating strategy.

Figure 2: Sustainability in the Drivetrain – Impact of Development Phase on Lifecycle GHG Emissions

The AVL PSO development methodology was used to optimize the EDU’s dimensions, simulating numerous variants to evaluate efficiency and performance under varying parameters. The basic design specification was derived from system simulations, with components and operating strategies already optimized during the early concept phase.

Outcome of this design evolution process is a unique system featuring key elements to support the lowest possible energy consumption in the vehicle. The gear-set features a single stage transmission with double helix gears, reducing mechanical losses in high torque and speed operating conditions by -16 % compared to conventional designs. In moderate torque and speed losses are reduced by 11 %. To enable compact packaging of the two e-Motors a planetary differential is used which could be packaged inside the double helix final drive gear with an axial length of less than 80 mm. The lightweight design reduces weight by -15 % to -20 % compared to conventional solutions.

An oil catch tank is positioned at the differential gear to collect oil effectively. This collected oil is then distributed to various components, including gears, bearings, and the dog clutch. Besides securing proper lubrication of the system the oil catch tank also lowers the oil level in the transmission sump, thus reducing splash-losses while the vehicle is running. The key element for enabling the operation of the boost electric motor is an electromechanically actuated disconnect clutch located on the e-Motor shaft. When it is not engaged, it is ensuring
operational efficiency.

To ensure safe operation of the dog clutch a special simulation experiment was set up to analyze the impact of the stator windings magnetic field on the dog clutch’s actuation force. Based on this investigation, using the advanced in-house simulation capabilities, it was possible in a virtual stage to evaluate a safe operation of the dog clutch under all operating conditions.

With introduction of the disconnect clutch enabled the implementation of an operating strategy, further contributing to highest possible system efficiency hence contributing to lowest possible energy consumption.

Design-to-CO2 Methodology

Considering the complete life cycle as a system with certain limits is essential for a valid analysis. Automotive manufacturers can influence most scope 1 and 2 emissions according to the Greenhouse Gas (GHG) Protocol Corporate Standard (2) and have certain but not full control of the upstream scope 3 emissions of the supply chain, as well as the scope 3 emissions downstream in the usage and recycling phases (3).

In product life cycle modelling, it is important to know the qualitative patterns for CO 2 e influenceability, determination and the actual occurrence to define appropriate optimization measures at the right times.

FIGURE 2 shows an ideal-typical pattern for the product life cycle of a Battery Electric Vehicle (BEV) assuming a European 2023 electricity mix in the production and in-use phase (1). It is shown that the CO 2 e influenceability decreases significantly during the later phases described. Although the majority of CO 2 e emissions occur during the production phase and typically need to be offset during the in-use phase when compared to other powertrain technologies, the development phase has the most significant impact on the CO 2 e footprint.

By integrating life cycle assessment (LCA) methodologies and sustainability criteria from the outset, developers can evaluate and compare the environmental impacts of various powertrain technologies. This proactive approach enables the identification of technologies that not only meet performance and cost requirements but also minimize CO 2 e emissions throughout the product’s life cycle. Consequently, making informed decisions early in the development process ensures that the chosen technology aligns with sustainability goals, leading to a more environmentally friendly product.

Through the integration of these cutting-edge technologies, AVL enables OEMs to deliver electric powertrains that excel in performance, efficiency, and sustainability. This advancement constitutes a significant milestone toward fulfilling the automotive industry’s climate objectives while preserving competitive product offerings.

Real Life Demonstrator

From the outset, the goal was to transfer the resulting technology into customer applications, aiming for comparable efficiency and consumption values in the target vehicle. When the EDU was integrated into a customer vehicle based on the original design, a slight efficiency loss was initially observed due to different driving conditions and load points. However, the efficiency still significantly improved the customer’s baseline EDU. To meet the original efficiency targets, goal-oriented adjustments were necessary. Subsequently, the electric motor topologies and gear ratios were optimized. The adaptation process included detailed investigations to improve efficiency under the boundary of materials usage comparable to benchmark solutions. All modifications were made with the updated customer load profile and the geometric constraints of the target vehicle in mind, ensuring seamless integration. Vehicle simulations confirmed the effectiveness of these measures, achieving an average customer cycle efficiency of more than 94 %.

The EDU was tested both on a test bench and in the vehicle to validate system efficiency. While the test bench results did not exceed the 94 % cycle efficiency target, further optimization of the operating strategy for in-vehicle use led to an average efficiency of 94.4 % during real-world testing, confirming the achievement of the project goals.

Conclusion

AVL has developed a high-efficiency electric drive unit (EDU) achieving over 94 % cycle efficiency under WLTP and CLTC standards, with vehicle energy consumption below 10 kWh/100 km. The EDU features a dual-motor configuration with permanent magnet synchronous machines, a single-stage double helical gears transmission, and a dual SiC inverter system, optimized through AVL’s Powertrain System Optimizer. Innovations include a lightweight, compact design with reduced mechanical losses and an electromechanically actuated disconnect clutch to enhance efficiency. The development incorporated lifecycle CO₂ assessments to align with sustainability goals, emphasizing early-stage optimization to minimize emissions. Real-world vehicle integration confirmed the system‘s efficiency, reaching 94.4 % in testing, demonstrating a significant advancement in electric powertrain performance and environmental impact reduction enabled thorough AVL technology and engineering methodology.

Validated Outcomes:

• Achieved an average EDU efficiency of more than 94 % in real-world testing scenarios
• Recorded 94.4 % efficiency in customer-specific driving cycles

Quotes:

• „>94 % EDU efficiency and <10 kWh/100 km energy demand – validated on the road, not just in simulation.“
• „Design-to-CO2e turns sustainability into an engineering parameter, not a marketing claim.“

Our future hybrids are designed to fit in all current BEV platforms

In addition to dedicated hybrid transmissions, Horse Powertrain also supplies dedicated combustion engines and complete drive modules. At the 28th CTI Symposium in Berlin last December, we spoke to Ingo Scholten, CTO of Horse Powertrain, about developments in current and future hybrid technology.

Mr. Scholten, Horse Powertrain has a broad portfolio of hybrid drives, but also produces its own dedicated hybrid engines and ICEs. That’s unusual for a Tier 1 supplier …

It is. There used to be a lot of ‘transmission-only’ suppliers for manual transmissions, automatics etcetera. But usually, OEMs made their engines and dedicated hybrid transmissions, or DHTs, in-house. Now we offer both – as a system supplier. That makes us quite special to our partners. Instead of just components, we can also offer entire drive systems – plus full integration support, including topics like emissions and homologation.

What are customers asking for?

Firstly and naturally, we still make drives for Geely and Renault, our parent companies. The Renault E-Tech hybrid, for instance, is now in its third generation. For Mercedes, we supply a 1.5-liter combustion engine for mild hybrids. In China, we’re developing our dual-motor DHTs, which now use dual-shaft transmissions instead of planetary gearing in earlier years. And we’re talking to other customers in Europe and the US. The demand there for full hybrids is even stronger than in China, but they also want PHEVs. We are discussing range extenders more and more, too. In China, it’s mostly long-range PHEVs with a parallel option; they have big traction motors, and drive like EVs. In Europe, drivers still use manual transmissions so multi speed system are accepted even in combination with electrification. But in China, multi-speed transmissions can be a problem because customers there expect an EV driving experience.

Dual-motor hybrid drives are gaining ground. When do you use serial-only, and when is serial-parallel better?

For maximum efficiency, including on highways and rural roads, you’d normally use serial-parallel – mostly P1 and P3. A serial-only drive would cost you 4-5% in efficiency. Parallel or multi-speed transmissions are better for higher tractive force requirements. P2 still has its place for small vehicles in segments A or B. And if you already have an all-wheel-drive system with an electric rear axle, P2 is fine there too; you don’t really need a hybrid drive with two electric motors in the front then. P2 can also work when OEMs design vehicles as ‘BEV native’ or ‘BEV first’, respectively. Space is limited, so a P2 with a single electric motor can be practical when a market needs a hybrid variant of the BEV.

Looking at P1/P3 hybrids, we’re seeing solutions with a single fixed gear, and solutions with two, three, or four gears. What do you think will prevail?

When markets want cars that ‘drive like a BEV’, it makes sense to have fewer gears. Often, just one is enough. For high towing capacity, you can use multiple gears to modulate tractive force. When customers ask us for advice, we often recommend either a large traction motor with one fixed gear or a powertrain with four gears and a smaller traction motor. As I mentioned, Renault has a successful solution that’s now in its third generation.

Many OEMs still need two vehicle platforms; others are moving to ‘BEV first’ and using a BEV platform for hybrids, too. What’s your approach?

That’s currently one of our main topics, as I showed in my presentation here at CTI. Some vehicles still use traditional hybrid architectures, which require certain compromises; others use BEV-only architectures. A hybrid drive with one or two electric motors requires more space than an ICE-only drive, whereas a BEV drive requires much less. So, if you optimize a vehicle’s front end for BEV, the installation space is shorter and, above all, narrower. The subframe mountings are configured differently, the drive shafts sometimes go in front of the axle. And then a traditional hybrid drive won’t fit. You need a hybrid drive design that fits within a BEV vehicle architecture without requiring OEMs to compromise their BEV optimization.

Which of your products meet that requirement?

Firstly, there’s our highly compact HORSE G10 for range extenders. It has a two-cylinder boxer engine with a compact pushrod design and a generator mounted directly on the crankshaft. Then we developed the HORSE C15, a range extender as well. This can be installed either vertically or horizontally. And then we have the Future Hybrid System, which is available in P2 or P1/P3. According to our research, it fits most of the dedicated BEV platforms currently available. So, if European customers with a BEV-first approach want a hybrid derivative for their platform, they can use these powertrains while still meeting all the BEV crash-test requirements.

You also offer dedicated hybrid combustion engines. What are their thermal efficiencies, and how much more is possible?

We are in production with over 44 percent break thermal efficiency. And those are figures from engineering, not marketing. We’re aiming for 49-50 percent. But to get there, we need to implement a few more technologies – for instance, lean combustion. We also then need to design exhaust systems that won’t significantly increase overall system costs. On the other hand, ICE dynamics are lower in serial operation, so that simplifies exhaust after-treatment to a certain extent. For tomorrow’s lean-burn engines, the key is to keep lambda above 2.2 as much as possible so after-treatment doesn’t get too complex.

Ingo Scholten during his presentation at the CTI Symposium 2025 in Berlin

How do you rate the potential of synthetic fuels in terms of lower CO2 emissions?

Nobody expects all the markets to switch to synthetic fuels in the short term. But it could well be a gradual process. In five years’ time, maybe we could add five percent of synthetic fuels, then later fifteen percent, or twenty. The really good thing is that you can reduce CO₂ across your whole existing fleet. Methanol is another field in which Geely is working. They started selling methanol engines in 2013. Originally, these were 100 percent methanol, designed for taxi fleets in regions where methanol was basically a by-product of coal mining. But now they’re working with bio-methanol and trying to create a circular economy there. At last year’s Vienna Motor Symposium, Geely presented onboard CO₂ capture for trucks, for example. Some innovations are just getting started, but we’re already seeing potential here and there.

The EU Commission has just reopened the window slightly for combustion engines after 2035. What do political decisions like this mean for Horse Powertrain?

None of our products is specifically designed for Europe. Our product strategy is very broad, with products we use in the European market, Brazil, India, and elsewhere. So, in terms of capacities and defining technical requirements, decisions about the time after 2035 don’t affect us that much. As a globally operating company, we offer solutions that can meet the requirements of various and changing markets.

Interview: Gernot Goppelt.

We Believe Polymer is the Sweet Spot for Solid-state Batteries

Adrian Tylim, Head of Business Development, Blue Solutions

Blue Solutions makes solid-state batteries in France and Canada. Series production is scheduled to begin in 2029, with significant advantages in energy density, cost, and safety, says Adrian Tylim, Head of Business Development. On the CTI Symposium Novi in May 2025, we discussed the prospects for solid-state batteries, and the company’s polymer-based technical approach.

Mr. Tylim, what are the functional challenges when developing solid-state vehicle batteries?

There are several. It’s a very competitive industry that attracts money, specifically for advanced and solidstate batteries. Many companies say they have solid-state batteries, but some may just produce small samples in a lab. When you start putting them into an application, it’s tough to increase the size of the cell and maintain or improve the performance. In the lab, the cell is usually the size of a coin, and increasing the size, voltage, etc., is a challenge. The second challenge is that you want to produce quickly, and on a large scale. For that, you need to develop a perfect process, which requires a lot of innovation. Then you have requirements in terms of safety and performance, and issues with decoupling from risky material supply chains. And of course, you want to produce the best product. Not many companies can meet those requirements in line with customer expectations.

In terms of production, what advantages do you have compared to ‘conventional’ Li-Ion batteries?

Lithium-ion batteries are easy to produce and have become very cost-competitive on a large scale. They are made all over the world, they have been manufactured and deployed for decades, and the technology is still improving. So anything we design to replace Lithium-ion must have specific advantages. One main focus is safety. Lithium-ion batteries have a liquid electrolyte. When a cell is defective, you get thermal runaway: the cell ignites, and the fire propagates from cell to cell. Our solid-state batteries have a solid electrolyte that doesn’t catch fire as with lithium-ion cells. We chose an electrolyte that surpasses the melting point of the lithium anode, which is the key variable in terms of thermal stability. The second main focus is manufacturing at cost and integrating the technology into the vehicle. Other solid-state advantages are longevity, more charging cycles, and higher energy density.

What kind of electrolyte material do you use?

Our material is a solid-state polymer. In the battery world, we talk about solid-state materials and semisolid-state materials, which contain a little liquid. For strictly solid-state, you have either ceramics or polymers. And within ceramics, you have oxides and sulfides. We chose a polymer material for several reasons. One is that Blue Solutions has a legacy of making films and ultra-thin films. We have developed a very simple process with a small manufacturing footprint. We make everything from raw materials. We extrude the lithium metal anode, the polymer electrolyte, and cathode. In the case of the anode, we start with a lithium metal cylinder. We extrude it at high speed, make it very thin, wide, and consistent, and then roll it. We do similarly with the polymer electrolyte. For the cathode, we have different dry coating or extrusion processes. And then we slit them and stack them to form our cell.

Speaking of so-called semi-solid-state technology, how do you rate its prospects?

Automotive batteries often have 100 layers, or 50 double layers. Whenever you charge and discharge the batteries, the stack basically expands and contracts. It’s a process we call ‘breathing’. So let’s say a vehicle is going to be out there for ten years. To ensure longevity, you must ensure all the interfacial contact between those layers stays intact. With ceramic materials, you need a lot of pressure to maintain that contact – between 5 to 20 bar. For that, you need a lot of mechanical components such as springs. But the more mechanical components you use, the less space volume is available to put energy storage inside the car, and the more complex and expensive it becomes. So we opted for a polymer material, which is elastic, so the interfacial contact remains intact with very little pressure and minimal components needed. Semi-solid attempts to do the same thing as we’re doing with our polymer, only using a ceramic material with a porous structure that contains some liquid. So while polymer may not be the best ionic conductor, when we look at all other beneficial aspects, we believe polymer is the sweet spot.

What are the USPs of your Gen 4 technology and Blue Solution’s capacities?

So far, we’ve made more than three million cells. Most of them fitted to commercial vehicles starting in 2011. Since then, there have been many improvements and lessons learned, which we have integrated in line with the requirements of our automotive customers. For example, the ability for the electrolyte to work at room temperature, even as the battery functions in temperatures from -20 to 60 °C. Additionally, our cells have been performing over 3,000 cycles, far exceeding the typical OEM benchmark of 1,000. This allows us to use an even thinner anode. The thickness is now <20 μm, compared to 60 μm in the third generation. Also, we can now service different vehicle market segments by using different cathode materials, like NMC or LMFP, and varying energy densities of up to 450 Wh/kg. After all, a Ferrari and a Fiat have different requirements. And by varying the cathode materials, we can scale the costs and performance of our cells. We are currently working with three automakers: BMW, and two others in the Top Five. We’re also cooperating with a Taiwanese electronics company, and we’re looking at twowheelers and other areas. Right now, we are at a point where we’re tweaking the chemistry and the form factor, for example, prismatic or pouch cells, etc. We are in the validation phase and expect to start series production around 2029.

How is the supply situation for the raw materials in your cells?

Sustainability is a core development goal for us. At the end of life, we can reuse all critical materials to produce new cells. We have also filed a new patent to extract lithium metal from the cells. The good thing is that we never use materials like copper. For our cathode current collector, for example, we only use aluminium. And for the anode, the collector is the lithium-metal foil itself. Also, polymer materials are not rare, so we have several suppliers – not just China. I don’t see any problems with the supply chain. And we have 20 years of experience in locating and sourcing materials for iron phosphate, lithium, and so forth.

How do energy density and costs compare to current state-of-the-art batteries?

That’s one of the most critical questions for customers! I could give you today’s figures, but it wouldn’t help much because our goals for series production in 2029 are 20 to 40 % higher density than the best lithium-ion battery, at unit costs of 20 to 40 % less. That’s the target we think we can achieve. When visitors tour our manufacturing plant, they are amazed at how simple our manufacturing is, with such a small footprint. For example, there’s no need for the calendering process used by lithium-ion battery manufacturers . And there is no need for an electrolyte filling process. So we save money on equipment, around 20 or 30 % of the CAPEX which should impact the price of the final product. And finally, another benefit is that there are fewer environmental requirements due to our simpler, which again lowers the costs.

When will we see your technology on the streets, and what market penetration do you expect?

As I said earlier, our goal is to start production in 2029. It’s hard to predict, but we think solid-state batteries can reach a market penetration of 5 % in 2030 and about 8 % in 2035. Based on what we see, and on analyses from some of the best sources, that seems realistic.

Interview: Gernot Goppelt