Horse H12 Hybrid Concept Engine Promises 44.2% Brake Thermal Efficiency

Horse Powertrain says it has developed a new hybrid engine that can deliver up to 71 miles per gallon combined, at least under the European WLTP cycle. The engine, called the H12 Concept, is an evolution of the company’s existing HR12 unit and is claimed to reach a peak brake thermal efficiency of 44.2 percent.

That is a strong number for any combustion engine. It runs a high 17:1 compression ratio and is designed to operate on 100 percent renewable fuel, which is a big part of its pitch.

Technically, it is more than just a tweaked engine. The H12 uses a next-generation EGR system, an optimized turbocharger, and a high-energy ignition setup. The hybrid gearbox has also been reworked to improve energy management and reduce internal friction, all in the name of improving efficiency. Horse says the 71 mpg figure is measured against the average European passenger car, so it is meant to show real-world relevance rather than lab-only bragging rights.

The project is being developed alongside Repsol, and the two companies have already built and validated two prototypes. Horse is now preparing for production and expects the first vehicle equipped with the new hybrid system to be ready early this year.

What makes this interesting is the positioning. Instead of waiting for full electrification to solve everything, Horse is arguing that highly efficient combustion engines paired with renewable fuels can cut emissions right now. Whether it lives up to the headline numbers in everyday driving remains to be seen.