HORSE H12 Hybrid Powertrain on 100% Renewable Gasoline
Horse Powertrain, through its Horse Technologies division, and Repsol have unveiled a next-generation hybrid powertrain that delivers ultra-high efficiency and low fuel consumption while running on 100% renewable gasoline.
The HORSE H12 Concept engine upgrades the combustion system and cuts internal losses. It achieves a peak brake thermal efficiency (BTE) of 44.2%. It reduces vehicle fuel consumption by 40% (compared with the 2023 average passenger car new registration in Europe)1 to below 3.3 litres per 100 kilometres standardised European testing (WLTP).
Higher efficiency cuts fuel consumption and CO2 emissions in the same proportion. When a mid-sized car uses the 100% renewable fuel and drives an average of 12,500 kilometres per year, the HORSE H12 Concept powertrain cuts emissions by 1.77 tons of CO₂ per year versus a vehicle with a traditional fuel and combustion engine. 1, 2
The hybrid powertrain system pairs the HORSE H12 Concept engine with a refined hybrid drivetrain. It upgrades the HR12 engine with an innovative combustion system that operates at a 17:1 compression ratio, a new-generation exhaust gas recirculation (EGR) system, an optimised turbocharger, a high-energy ignition system, and an improved hybrid energy management system. Repsol lubricants also reduce internal friction to support low fuel consumption.
Teams at the Horse Technologies Division in Valladolid and the Repsol Technology Lab in Madrid lead the project. They have built the first two prototypes and validated performance, and they plan to present the first demonstrator vehicle in early 2026. They also position this milestone as the first step towards industrial production of highly efficient hybrid engines.
This project supports the mobility sector’s transition to net-zero and adheres to the principle of technology neutrality. It also shows how innovation can deliver near-term CO2 reduction solutions.
More than 97% of Europe’s current vehicle parc (ACEA) still relies on combustion, so the sector needs solutions that cut CO2 emissions today. Highly efficient engines and alternative fuels can complement electrification, hydrogen, and other emerging technologies on the road to net-zero mobility.
To scale these solutions, the current revision of CO₂ standards for light-duty vehicles needs a clear, long-term framework. Policymakers recognise the role of highly efficient engines powered by renewable fuels in the road to decarbonisation and support a technology-neutral approach beyond 2035 to drive innovation and industrial investment.
Luis Cabra, Executive Managing Director of Energy Transition, Technology, Institutional Affairs and Deputy CEO of Repsol, states: “This collaboration shows decarbonisation can be accelerated through innovative and accessible technological solutions. The use of 100% renewable fuels is a net-zero-emission solution that complements electric vehicles and decarbonises the transport sector. Supporting clear and ambitious regulation that drives investment in renewable fuels and highly efficient engines is essential for Europe to reduce transport emissions faster, more competitively, and effectively.”
Patrice Haettel, Chief Operating Officer at Horse Powertrain and Chief Executive Officer at Horse Technologies, adds: “The HORSE H12 Concept is an example of how highly 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 cut emissions. This is why we advocate a technology-neutral approach that enables innovation across all solutions - electric, hybrid, range extenders and low-carbon fuels.”
In October, Repsol reached a technological milestone when it produced gasoline of 100% renewable origin at an industrial scale at its Tarragona facility. This product is compatible with existing gasoline-powered vehicles and requires no modifications. Drivers can already buy Nexa 95, Repsol's highest-quality 95-octane renewable gasoline, at 30 service stations in Spain.
Repsol also supplies renewable diesel at nearly 1,500 service stations in Spain and Portugal, making it the largest renewable-fuel distribution network in Europe.
Repsol leads renewable fuel production in the Iberian Peninsula and operates the first industrial plant dedicated to the production of 100% renewable fuels from waste in Cartagena (Spain). The company will start operations at a second plant in Puertollano in 2026. Repsol will also launch a demonstrator e-fuels plant in Bilbao in 2026.