In Brief
The experimental Dacia Duster integrates a hybrid gasoline engine, the Horse H12, and runs on Nexa 95, a renewable gasoline, touting an impressive fuel economy of 3.3 L/100 km. This prototype highlights the potential of an innovative alternative to 100% electric powertrains, blending energy efficiency with lower CO₂ emissions. While the technology shows promise, mass production and the fuel’s availability remain limited at this stage. The Duster serves primarily as a technological showcase, opening a debate about the future of low-carbon internal combustion engines.
From a distance, this Dacia Duster looks like any other on the road. Yet beneath its skin, it doubles as a mobile lab for a simple question: what if, instead of abandoning internal combustion engines, we cut emissions by making engines more efficient and by changing the fuel they use?
That is the challenge taken on by Horse Powertrain and Repsol. The former developed a highly fuel-efficient gasoline hybrid, the Horse H12 Concept. The latter proposes a new kind of fuel, the Nexa 95, a fully renewable gasoline produced from organic residues. Together, they have already tested this pairing in a Dacia Duster consuming 3.3 L/100 km on a route between Valladolid and Móstoles in Spain. This prototype, not yet slated for series production, raises an important question: could this engine-fuel duo point to a new direction for combustion engines?
A Dacia Duster showing 3.3 L/100 km to demonstrate the potential of combustion
At the heart of this “laboratory Duster” lies a three-cylinder gasoline engine derived from Renault-Nissan’s well-known HR12 block. Rebranded H12, the engine has undergone significant modifications: a compression ratio of 17:1, a next-generation exhaust-gas recirculation system, an optimized turbocharger, high-energy ignition, and lubricants tailored to minimize mechanical losses. All of this operates within a hybrid drivetrain with enhanced energy management. The claimed thermal efficiency tops out at 44.2%, compared with the best current gasoline engines at around 40–41%, and a WLTP cycle fuel consumption under 3.3 L/100 km, roughly 40% lower than the average new gasoline car registered in Europe in 2023.
The engine isn’t just a lab curiosity. Two prototypes have passed bench tests, and a real-world run from Valladolid to Móstoles tested it in a Dacia Duster. Behind the project is a true industrial venture: Horse Powertrain, a joint venture formed in 2024 by Renault and the Chinese automaker Geely, with a 10% stake held by Aramco. Based in London, with an R&D center in Valladolid and manufacturing sites in Spain (Valladolid and Seville), the firm foresees a production capacity of around five million engines per year. At present, no manufacturer has officially announced integrating the H12 into a production lineup. The Duster demonstrator remains a technology showcase rather than a model ready for dealership.
Nexa 95 renewable gasoline and the Horse H12: an option for combustion after 2035?
The second key element of this 3.3 L/100 km Duster sits at the fuel pump. Nexa 95, developed by Repsol, is a fully renewable gasoline with no trace of fossil oil. It is produced from organic waste from industrial activities, such as used oils, animal fats, or agricultural by-products, transformed into a fuel with an octane rating of 95. A crucial point for drivers: Nexa 95 is claimed to be fully compatible with all current gasoline engines without any modification. Repsol began industrial production in October 2025 at its Tarragona, Spain, facility, with a second plant planned for Puertollano in 2026, and a synthetic fuels project underway in Bilbao. For now, distribution is very limited: this renewable gasoline is available at only about thirty service stations in Spain, while Repsol’s renewable diesel is already sold at more than 1,500 outlets in Spain and Portugal. When paired with the H12 engine, this fuel could cut emissions by approximately 1.77 tons of CO₂ per year for a mid-size vehicle traveling 12,500 km, though the estimate depends on several factors, including fuel availability, which remains limited for daily use.
Beyond this demonstration, the challenge extends far beyond a single experimental Dacia Duster. Today, around 97% of cars in Europe still run on internal combustion. Reductions in CO₂ standards could recognize renewable fuels as a viable method to curb emissions after 2035, which would change the outlook for solutions like the H12–Nexa 95 pairing. Repsol emphasizes an “immediate solution” to lower emissions without waiting for a full fleet renewal, and Horse’s message is clear, as Jesús Francés, director of strategy and advanced engineering at Horse Technologies, puts it: “The enemy is CO2, not technology. This powertrain shows that efficient engines and renewable fuels can reduce emissions now, not in 20 years.” Yet a major unknown remains: without mass deployment of this fuel type and without a clear decision by manufacturers on industrializing engines like the H12, this 3.3 L/100 km Duster will remain mainly a proof of concept, not a station-ready reality.
Comparative Table
| Feature | Dacia Duster H12 + Nexa 95 | Conventional Gasoline Engine (2023, Europe) |
|---|---|---|
| Consumption (WLTP) | 3.3 L/100 km | around 5.5 L/100 km |
| Thermal efficiency | 44.2% | 40–41% |
| CO₂ emissions reduction | up to 1.77 t/yr for 12,500 km | not specified |
| Compression ratio | 17:1 | not specified |
| Availability of renewable fuel | 30 stations (Spain, 2025) | Classic stations |
Key Takeaways
- The experimental Dacia Duster with the H12 engine and Nexa 95 fuel records less than 3.3 L/100 km thanks to an advanced hybrid setup and a renewable fuel.
- The new Horse H12 engine achieves a thermal efficiency of 44.2%, higher than conventional gasoline engines.
- The Nexa 95 fuel, entirely derived from organic residues, is compatible with all modern gasoline engines.
- The H12–Nexa 95 pairing could cut up to 1.77 tons of CO₂ per year for a mid-size vehicle driving 12,500 km.
- The project remains a prototype, with no official consumer launch planned to date.
- Nexa 95 distribution remains very limited, which currently slows broad adoption.
FAQ
What is the real-world fuel consumption of the experimental Dacia Duster?
The Dacia Duster prototype equipped with the H12 engine and using Nexa 95 records consumption below 3.3 L/100 km on the WLTP cycle.
Is Nexa 95 compatible with all gasoline engines?
Yes, Nexa 95 is claimed to be fully compatible with all current gasoline engines without requiring modifications.
Will the H12 hybrid engine be commercialized soon?
No automaker has officially announced integrating the H12 engine into a production lineup yet. It remains a technology showcase.
Where can Nexa 95 be found today?
Nexa 95 is still limited to about thirty service stations in Spain, with expansion planned in the future.
What are the advantages of the H12 and Nexa 95 duo?
This pairing enables a meaningful reduction in fuel consumption and CO₂ emissions, offering a compelling alternative to full electrification.
