Drive Technology Hybrid Solutions and Efficiency Improvements in Focus

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Evolution or revolution – much is happening in the drive sector. This ranges from detailed improvements to individual engine components to new drive architectures and business models.

The trend towards more electric drives has already prompted some OEMs to scale back or outsource their development activities for combustion engines. Horse Powertrain is such a new company that emerged from the engine activities of Renault, Geely, and Volvo – including a stake from the Saudi Arabian oil company Aramco. Horse aims to act as an external and neutral partner in developing and producing hybrid drives or combustion engines for OEMs, thereby freeing them up to focus on their own development of battery-electric drives.

For this business model, a new hybrid drive was presented in 2025, the centerpiece of which is a 1.8-liter four-cylinder combustion engine with 80 kilowatts of power and 172 Newton meters of torque. It is paired with an electric motor (50 kilowatts, 212 Newton meters) that draws its energy from a lithium-ion battery with an energy capacity of 1.4 kilowatt-hours. The transmission and power electronics are also integrated into the overall solution from the outset, making the drive unit highly compact. A technical highlight of the drive, according to Horse, is the combustion engine operating on the Atkinson cycle, which is compatible with common flex-fuel mixtures containing up to ten percent ethanol and is designed to meet the Euro 7 emissions standard. According to CEO Matias Giannini, Horse has designed the hybrid drive "as a global solution" to cover many markets and vehicle segments.

Hybridization with Range Extender

Horse goes a step further with the concept of a separate range extender that could hybridize battery-electric vehicles as an add-on. The drive system, presented at Auto Shanghai, consists of a combustion engine, an electric motor, a transmission, attached drive shafts, and the complete electronics. According to Horse CEO Matias Giannini, the compact unit is "25 percent narrower and 20 percent more cost-effective than previous solutions" thanks to comprehensive integration. He also stated that it can be installed on the front axle of electric vehicles without requiring significant modifications to their architecture.

This would enable an electric all-wheel drive, as well as a type of "hybrid drive" with the combustion engine acting as a generator and range extender. The concept is also intended to be suitable as a replacement for a conventional gasoline or diesel engine in a combustion platform. The combustion engine operates with pre-chamber ignition and various fuels such as E85, ethanol, methanol, and synthetic fuels. According to Horse, the first vehicles with the Future Hybrid Concept are expected to hit the road in 2028.

Fully Electric Skateboard Chassis

Mercedes-Benz is set to introduce the new MMA architecture in 2025, which is expected to debut in series production with the new entry-level CLA model. The new MMA architecture is a so-called skateboard chassis, on which various body designs can be mounted. The 800-volt architecture enables a charging capacity of 320 kilowatts or up to 300 kilometers( ~186 miles) of range in ten minutes. It is planned that the charging unit will later also support bidirectional charging.

The permanently excited synchronous motor (PSM) with a silicon carbide inverter on the rear axle delivers up to 200 kilowatts and transmits its power to the rear wheels via a two-speed transmission. An additional PSM electric motor with 80 kilowatts on the front axle is optionally available, which is primarily activated during acceleration and can also be deactivated via a clutch for efficiency reasons. These structural efficiency measures, an optional recuperation capacity of up to 200 kilowatts down to coasting, as well as sophisticated operating modes, aim to reduce energy consumption to about twelve kilowatt-hours per 100 kilometers (~62 miles).

The battery features new cell chemistries and a cell-to-pack design. In the base version with lithium iron phosphate cells (LFP), it offers an energy capacity of 58 kilowatt-hours. In the top version with NMC technology, it holds 85 kilowatt-hours and has an energy density of 680 watt-hours per liter. According to Mercedes-Benz, this is approximately 20 percent better compared to the previous generation, and costs at the battery level have decreased by 30 percent.

Evolution Instead of Revolution at VW

Volkswagen has reduced the energy consumption of its APP310 electric drive (PSM with 310 Newton meters of torque, series production starting in 2020) not through a generational shift but through model maintenance measures. Since the new evolution stage APP350 is to be produced on the same line as the APP310 variant, new windings for the electric motor or a new cooling system were not considered. Instead, the focus was on detailed optimizations.

For example, by switching from silicon IGBT semiconductors (efficiency 94 to 97%) to SiC MOSFETs (efficiency 97 to 99%) from Bosch, which exhibit lower losses and thus reduced cooling requirements. Another measure is in pulse-width modulation (PWM), now utilizing not only continuous switching frequencies but also variable switching frequencies depending on speed and load conditions, as well as alternative modulation methods such as block operation and no-zero-pointer modulation.

Additionally, Volkswagen has reduced the sheet thicknesses in the stator, thus decreasing core losses caused by the change in magnetic fields. Furthermore, the circuit variant of the stator winding was switched from a star to a delta connection, and the number of parallel branches was halved to increase efficiency at customer-relevant operating points.

40 Kilometers More Range

Volkswagen identified potential savings in oil quality, where a particularly low-friction oil is now used. It halves the viscosity in typical operating temperature ranges, enabling up to twelve kilometers more range.

Through these measures, VW engineers were able to improve the efficiency of the APP350 drive compared to its predecessor, the APP310, in many mapping areas (primarily the operationally relevant ones), in some cases by up to ten percent. As a result, the new drive in the reference vehicle ID 4 saves about 36 percent energy during the WLTP cycle. This increases the range of the electric vehicle by up to 40 kilometers. Additionally, operational noise has been significantly reduced thanks to structural improvements to the rotor and new software functions.