The second car to launch as part of BMW’s electric i sub brand, following the i3, the i8 combines a three-cylinder turbocharged petrol engine producing 227bhp with a 129bhp electric motor and lithium-ion battery which can drive the car for 23 miles.

This allows the i8 to reach 62mph in 4.4 seconds on the way to an electronically limited 155mph top speed.

Final development work was completed at the start of March, the carmaker said, allowing the car to achieve new lower fuel consumption figure of 134.5mpg on the NEDC plug-in hybrid test, with a resulting cut in CO2 emissions too.

BMW claims the supercar will be capable of averaging more than 56mpg around town, and over 40mpg on the motorway – 50% better than a conventionally-powered model, owing in part to a low kerb weight of 1,485kg and an aerodynamic body.

CO2 emissions of 49g/km also place it ahead of fellow plug-in hybrid supercar, the Porsche 918 Spyder, which emits 79g/km.

Series production of the i8 will begin in April, and the car will launch in Europe’s biggest markets with first deliveries scheduled for June.