Porsche and BMW unveil hybrid super cars built for racing

Unveiled at the Frankfurt Motor show, the Porsche 918 Spyder can reach 60mph in less than 2.8 seconds, while BMW's futuristic i8 takes less than 4.4 seconds to reach the same speed.

But the sleek sports cars are designed to be fuel efficient as well as fast. Porsche's Spyder can also do 72 miles per gallon and is almost a third more fuel efficient than the Toyota's Prius, while the BMW i8 is even less thirsty as it can manage 113 miles per gallon.

Porsche's £537,000 offering is a carbon fibre supercar with a plug-in hybrid drive, making it the latest racing car manufacturer to try and make more eco-friendly cars sexy.

When tested around the famous racing circuit, Porsche said that the 918 Spyder completed the 12.8 mile track in just six minutes and 57 seconds. 

The hybrid car shaved 14 seconds off the previous Nurburgring record for a street-legal car, making it the fastest super car built for normal roads to race the course.

The company said: 'Never before has a supercar designed for everyday use offered such an impressive dynamic performance combined with the fuel consumption of a compact car.'

Wolfgang Hatz, member of the Porsche AG Board of Management in charge of research and development, said: 'We promised a great deal with the 918 Spyder, namely to redefine performance, efficiency and driving pleasure. We have kept our word.'

BMW has finally taken the wraps off its much-teased hybrid supercar, which has a top speed of 155mph and is capable of doing 113 miles per gallon.

The futuristic i8 is the car manufacturer's 'most advanced' sports car ever and is powered by a relatively small 1.5 litre turbocharged engine which, combined with an electric motor, generates 362 brake horsepower.

This gives the plug-in hybrid a 0 to 62mph time of just 4.4 seconds and an electronically limited top speed of 155mph.

The car is capable of being driven in electric mode for 22 miles at a top speed of 75mph and BMW claims the i8 can have its battery charged from zero to 80 per cent in less than two hours.

When fully charged and with a full tank of fuel, the four-seat i8 can be driven for around 310 miles before needing to be topped up.

BMW has been teasing the arrival of its more eco-friendly supercar for a long time with drawings of concept cars, but has now confirmed the car will go on sale in July next year and will cost £99,845.

The body is made of carbon and aluminum, while its shape means there is no need for a spoiler.

The company said: 'The new BMW i8 combines the performance of a sports car with the fuel consumption of a small compact car, boasting impressive efficiency and sustainability without forfeiting driving dynamics.