Horse Powertrain and Repsol have unveiled a new hybrid powertrain concept that they said cuts fuel use sharply while running on 100% renewable gasoline, as both companies make the case for combustion-based solutions in Europe’s decarbonisation push.
Announced in Madrid on Feb 16, the project centres on the HORSE H12 Concept engine, developed by Horse Technologies, a division of Horse Powertrain, with Repsol.
They said the system achieved 44.2% peak brake thermal efficiency and cut vehicle fuel consumption by 40% versus the 2023 average for newly registered passenger cars in Europe, bringing consumption to below 3.3 litres per 100km under the WLTP test cycle.
They also said that, when paired with Repsol’s 100% renewable gasoline, a mid-size car travelling 12,500km a year would emit 1.77 tonnes less CO2 per year than a comparable vehicle using a conventional combustion powertrain and fuel.
Horse described the H12 Concept as an evolution of its HR12 engine.
Both companies said the system combined a 17:1 compression ratio combustion setup, a new exhaust gas recirculation system, an optimised turbocharger, a high-energy ignition system, and an updated hybrid gearbox with improved energy management. They also said new Repsol lubricants helped reduce internal friction.
Teams from Horse Technologies in Valladolid, Spain, and Repsol’s technology lab in Madrid are leading the development work.
They said two prototypes have already been built and performance has been validated, with a first demonstrator vehicle due in early 2026. They described the project as a first step towards industrial production of higher-efficiency hybrid engines.
Both companies also used the launch to push a policy message. Horse and Repsol argued that Europe should keep a technology-neutral approach in future CO2 rules, including beyond 2035, so highly efficient engines running on renewable fuels are recognised alongside electrification, hydrogen and other low-carbon options.
Repsol said it began industrial-scale production of 100% renewable gasoline in Tarragona last October.
It said Nexa 95 renewable gasoline is now sold at 30 stations in Spain, while renewable diesel is available at nearly 1,500 stations across Spain and Portugal.
