Madrid – A fresh collaboration between Horse Powertrain and Repsol is aiming to redefine efficiency in the automotive industry with the development of a next-generation hybrid powertrain. The companies unveiled the HORSE H12 Concept engine, designed to run on 100% renewable gasoline, promising a significant reduction in fuel consumption and carbon dioxide emissions. This development arrives at a crucial moment as the transportation sector seeks viable pathways to net-zero emissions, and represents a potentially significant step beyond full electrification for many drivers.
The HORSE H12 Concept engine achieves a peak brake thermal efficiency of 44.2%, a substantial improvement over conventional engines. According to the companies, this translates to a 40% reduction in fuel consumption – bringing it below 3.3 liters per 100 kilometers based on standardized European testing (WLTP) – compared to the 2023 average for new passenger cars in Europe. When fueled by Repsol’s 100% renewable gasoline, a mid-size vehicle equipped with this engine is projected to emit 1.77 tons less CO₂ annually than a comparable vehicle with a traditional combustion engine and fuel, according to the methodology outlined in EU Directive 2018/2001 (Annex V, C).
Boosting Efficiency Through Innovation
The advancements within the HORSE H12 Concept aren’t simply about a single breakthrough, but a series of refinements. The engine is an evolution of the HR12 model, incorporating an innovative combustion system with a high compression ratio of 17:1. Further enhancements include a new generation exhaust gas recirculation (EGR) system, an optimized turbocharger, and a high-energy ignition system. These improvements are coupled with an enhanced hybrid gearbox featuring optimized energy management and reduced internal friction through the leverage of new Repsol lubricants.
The project, spearheaded by teams at Horse Technologies in Valladolid, Spain, and the Repsol Technology Lab in Madrid, has already yielded two working prototypes. A demonstrator vehicle is slated for presentation in early 2026, marking a key milestone toward the potential industrial production of these high-efficiency hybrid engines. The collaboration highlights a commitment to technological neutrality, demonstrating that innovation can deliver near-term CO₂ reduction solutions.
Renewable Fuels and the Future of Mobility
The significance of this development extends beyond the engine itself. The use of 100% renewable gasoline is central to the project’s environmental benefits. Repsol achieved a technological milestone in October 2023 by producing renewable gasoline at an industrial scale at its Tarragona plant. Repsol’s Nexa 95, a 95-octane renewable gasoline, is currently available at 30 service stations across Spain.
Repsol is similarly expanding its renewable fuel offerings, providing renewable diesel at over 1,500 stations in Spain and Portugal, making it the largest distributor of renewable fuels in Europe. The company is investing heavily in renewable fuel production, with a first industrial plant dedicated to producing 100% renewable fuels from waste located in Cartagena, Spain, and a second plant planned for Puertollano in 2026. A pilot plant for synthetic fuels is also slated to open in Bilbao in 2026.
A Complementary Approach to Electrification
With over 97% of the European vehicle fleet still powered by internal combustion engines, according to the European Automobile Manufacturers Association (ACEA), solutions like the HORSE H12 Concept are seen as a crucial complement to the ongoing shift towards full electrification, hydrogen, and other emerging technologies. The companies emphasize the need for a technology-neutral regulatory framework that recognizes the contribution of ultra-efficient engines powered by renewable fuels in decarbonizing road transport.
“This collaboration demonstrates that decarbonization can be accelerated through innovative and accessible technological solutions,” said Luis Cabra, Repsol’s Executive Managing Director for Energy Transition, Technology and Institutional Affairs. “The use of 100% renewable fuels is a net-zero emissions solution, complementary to electric vehicles, for decarbonizing the transport sector. Supporting a clear and ambitious regulation that drives investment in renewable fuels and highly efficient engines is essential for Europe to reduce transport emissions more quickly, competitively, and effectively.”
Patrice Haettel, Chief Operating Officer of Horse Powertrain and CEO of Horse Technologies, echoed this sentiment, stating, “The HORSE H12 concept is an example of how ultra-efficient engines and renewable fuels can reduce emissions today, without waiting for future solutions. As a company, we believe that relying on a single technology is not the fastest way to reduce emissions. We advocate for a technology-neutral approach that drives innovation in all solutions: electric, hybrid, range extenders and low-carbon fuels.”
The development of the HORSE H12 Concept engine and the expansion of renewable fuel production by Repsol represent a significant step towards a more sustainable future for the automotive industry. The next key milestone will be the unveiling of the demonstrator vehicle in early 2026, providing a tangible example of the potential of this technology.
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