ICE 2025+ | Improving the efficiency of spark-ignition engines in hybrid powertrains

In order to meet future CO2 limits, spark-ignition engine-driven vehicles (ICEV - internal combustion engine vehicles) must consume significantly less fuel. In the FVV „ICE 2025+“ research project, four university institutes from Aachen, Braunschweig, Darmstadt and Stuttgart are investigating various technology options for significantly increasing efficiency. The aim of the self-financed project is to optimise the powertrain system in such a way as to achieve the lowest possible consumption in real world operation. In relation to the new WLTP cycle (World Harmonised Light-duty Vehicles Test Procedure), this means achieving an average power efficiency of around 40 per cent, and even 50 per cent in individual operating points. Today’s passenger car spark-ignition engines achieve the best value of around 37 per cent, on average around 30 per cent. Within the project, new engine technologies are researched in interaction with electrified powertrains and synthetic fuels.

» In addition to electrification, highly efficient internal combustion engines integrated in hybrid powertrains as well as carbon-neutral synthetic fuels will make a decisive contribution to achieving the CO2 targets. «
Dipl.-Ing. Arndt Döhler (Opel Automotive GmbH)


It remains to be seen which powertrains, energy sources and transportation concepts will determine passenger and freight transport in 2050. In the short and medium term, energy-efficient hybrid vehicles and carbon-neutral fuels must make an effective contribution to climate-neutral mobility. For this reason, the FVV funds pre-competitive collective research projects from its own financial resources in order to contribute to the long-term goal of "zero impact emission mobility".

» CO2 emissions from road transport must fall significantly over the next decade. It is essential that industry and science team up to meet this challenge. «
Dipl.-Ing. Dietmar Goericke (FVV eV)


The researchers' methodological approach consists of combining various pre-selected technologies - such as higher compression ratios or water injection - and investigating their impact on system efficiency. In order to adapt the powertrain system to real driving conditions, various vehicle classes as well as hybrid variants - from mild 48-volt to high-voltage hybrid drives - will be included in the study. The participating researchers work closely together. The first work package, for which the Institute for Internal Combustion Engines and Powertrain Systems (vkm) at Technische Universität Darmstadt is responsible, lays the foundations for vehicle simulation. The second part of the project, engine simulation, which is being carried out at the Institute for Internal Combustion Engines and Automotive Engineering (IVK) at the University of Stuttgart, consists primarily of being able to make binding statements about increases in efficiency through various combinations of technologies with the aid of rapid calculation methods. Within "ICE 2025+", essential measures to increase efficiency will not only be simulated, but also tested on a single-cylinder research engine. The Institute for Internal Combustion Engines (ivb) at Braunschweig Technical University is responsible for setting up and operating this test engine. Within the fourth work package, the influence of carbon-neutral fuels on engine behaviour is investigated at the Chair of Internal Combustion Engines (vka) at RWTH Aachen University.


The outcome of the research project will be available in spring 2021. A follow-up project is planned.


ICE2025+: Ultimate System Efficiency | Limits to increasing the efficiency of spark-ignited engines in hybrid powertrains | Project No. 1307



FVV Funding

1.000.000,00 EUR

Time Period
2018-02-28 to 2020-10-31

Research Association for Combustion Engines (FVV) eV

Lyoner Strasse 18
60528 Frankfurt am Main


Dipl.-Ing. Arndt Döhler
Opel Automobile GmbH

Dr.-Ing. André Casal Kulzer
Dr. Ing. h.c. F. Porsche AG

RTD Performers

1 | Institute of Automotive Engineering (IFS), Chair of Automotive Powertrains, University of Stuttgart

Head of research:
Prof. Dr.-Ing. Michael Bargende

2 | Institute for Internal Combustion Engines and Powertrain Systems (vkm), Technische Universität Darmstadt

Head of research:
Prof. Dr. techn. Christian Beidl

3 | Institute for Combustion Engines (vka), RWTH Aachen University

Head of research:
Prof. Dr.-Ing. Stefan Pischinger

4 | Institute of Internal Combustion Engines (ivb), Department of Mechanical Engineering / Production and Systems Engineering, Technische Universität Braunschweig

Head of research:
Prof. Dr.-Ing. Peter Eilts

Technical University Braunschweig

Institute of Internal Combustion Engines (ivb)

Hermann-Blenk-Str. 42
38108 Braunschweig

RWTH Aachen University

Chair of Thermodynamics of Mobile Energy Conversion Systems (tme)

Forckenbeckstrasse 4
52074 Aachen

University of Stuttgart

Institute of Automotive Engineering (IFS)/Chair of Automotive Powertrains

Pfaffenwaldring 12
70569 Stuttgart

Technische Universität Darmstadt

Institute for Internal Combustion Engines and Powertrain Systems (vkm)

Otto-Berndt-Str. 2
64287 Darmstadt

Research Association for Combustion Engines eV

Lyoner Strasse 18
60528 Frankfurt am Main
T +49 69 6603 1345