The Fisker Karma sports car has achieved an average economy of 135mpg in independent tests.
The Karma is driven by a pair of electric motors, but has a 2.0-litre turbocharged engine that acts as a generator when the batteries run low. Vauxhalls Ampera, which goes on sale next year, uses a similar system.
In tests, the Karma achieved 135mpg on the average cycle and emitted just 51g/km of CO2. That puts the car in the lowest company car bracket of 5%, and it will be exempt from road tax when it goes on sale in the UK.
It can run for 51.6 miles on all-electric power alone, and has a total range of 300 miles. In the same independent tests, the car averaged 31mpg when driven in Sport mode.
In all-electric mode it can get from 0-62mph in less than eight seconds and reach a top speed of 95mph. Switch to Sport, which starts the petrol generator, and the 0-62mph time is cut to just 5.9 seconds, while top speed increases to 125mph.
'We are naturally very pleased with the results, which show we have delivered better than our anticipated fuel efficiency figures,' said Fisker Automotive ceo Henrik Fisker. 'We believe the Karma is a car well-suited to the lifestyles of many people in Europe, and these results reinforce that position.'