The unit beat off competition from the range extender and full electric units in the BMW i3 plus the Ford 999cc EcoBoost unit which scooped the overall title and the sub 1.0-litre category.

Tesla adds the latest accolade to a long list of awards for the Model S, including Motor Trend Car of the Year and Automobile Automobile of the Year in the US. The electric car company also announced last August that its Model S had achieved the best safety rating from the National Highway Traffic Safety Administration (NHTSA) of any car that's ever been tested in history.

The 16th International Engine of the Year Awards were judged by an 82-strong panel of international experts, and winners were announced at a ceremony at Engine Expo 2014 in Stuttgart, Germany on 25th June.

To qualify for inclusion in the Green Engine category, an engine must have been housed in a passenger car that was on sale in more than one country as of June 2014, have been designed with fuel economy as a priority, and employ intelligent technologies and engine subsystems to reduce all types of emissions, including particulate matter and NOx.