Mercedes is attempting to beat rival Volkswagen to the market with the world’s first mass produced petrol engine that combines the torque and fuel economy of modern diesels with cleaner emissions. Efficient features that have been added to the engine include direct injection, turbocharging and variable compression. Unlike the VW design, the Mercedes engine doesn’t require special synthetic fuels and runs on regular petrol.

The initial concept engine is a small 1.8L four-cylinder, which delivers an amazing 238hp (175kW) and 400Nm of torque. Initial tests have seen fuel consumption at around 39mpg (6L/100km), and this was in a large S-class saloon. The engine works by using sparkless ignition, like a diesel, during low load conditions, and switches back to using a spark plug on cold starts and under full load.

Engineers have another trick up their sleeves. Fuel economy will improve even further with the addition of new hybrid technology, including an integrated starter-generator attached to the flywheel.