Researchers at MIT have been testing a prototype of a new internal combustion engine design that’s said to improve fuel-efficiency by up to 25% and runs on regular petrol. Labeled homogeneous charge compression ignition (HCCI), the new technology works by achieving combustion with only compression of the air-fuel mix rather than using a spark plug.

Last month Mercedes-Benz unveiled its DiesOtto concept engine, a new design that works in the same way as the HCCI system and was tested to achieve 39mpg in an S-class saloon. Volkswagen, too, is developing its own version of the system but unlike the MIT prototype and Mercedes’ DiesOtto, which run on regular petrol, the VW design requires a special synthetic fuel.

A professor at MIT, John Heywood, says that efficiency of engines could be improved even further by combining other fuel saving technologies such as forced-induction and direct injection concepts. You can read more about HCCI by clicking here.