Toyota develops world’s ‘most thermally efficient’ petrol engine

Toyota has developed a 2.0-litre, four-cylinder petrol engine that is said to have a thermal efficiency of 40 percent – just 1 percent short of what the Prius offers with its 1.8-litre hybrid powertrain.

Toyota states that the engine can achieve unparalleled levels of fuel economy as a result of new friction-reducing technology and more efficient exhaust and cooling systems. In general, petrol engines have a thermal efficiency of about 20-25 percent.

The new 2.0-litre petrol engine, which peaks at 171hp, will also get hybrid electric power. In this guise, it will match the Prius’ 41 percent thermal efficiency but with more performance thanks to its larger capacity. This hybrid powertrain is expected to be introduced on the upcoming Auris, which is scheduled for reveal at the Geneva motor show next week.

It will be one of two hybrid powerplants offered in the new Auris, with the existing 1.8-litre hybrid powertrain still being the entry point, albeit in an updated form. The new 2.0-litre engine will also find its way onto other models built on Toyota’s new global architecture (TNGA) in the coming years.

Toyota has also developed a more efficient CVT gearbox that uses the world’s first gear drive for initial acceleration. This essentially gives the gearbox the quicker off-the-line response of a standard automatic but enables the higher efficiency of a CVT when moving.

Meanwhile, the carmaker has created a torque vectoring system for petrol all-wheel-drive models that can decouple the front axle for a pure rear drive. This system will be introduced in Toyota’s all-wheel-drive and off-road models in the near future, with claims of improved fuel economy.