The Department for Transport has launched an online index to help people choose the most environmentally-friendly efficient car.

The listing can be searched according to categories such as supermini, family or estate, and using specifics such as transmission and fuel type. It will provide users with the most fuel-efficient vehicle within the parameters set.

The scheme is part of the government's Act on CO2 campaign to tackle climate change, launched earlier this month.

Transport minister Jim Fitzpatrick said: 'Climate change affects everyone and everyone can make a contribution to tackling it.

'By choosing the car with the most fuel efficient engine in its class, drivers could reduce their engine CO2 emissions by 24 per cent and potentially save a quarter on fuel costs.'