It would be greener and cheaper for many motorists to keep their car for as long as it is reliable rather than trading it for a new car, according the Environmental Transport Association (ETA).

Before a new car has even been turned on, before it even leaves the showroom, it has already accounted for 6 tonnes of CO2 emissions just in the construction, delivery, and marketing.

A spokesperson for the ETA said: "Swapping a thirsty and polluting older car for a lighter, more fuel-efficient model can make environmental sense if you are doing a high mileage, but if you do relatively few miles it makes sense to keep your car for as long as it is reliable. The greater your annual mileage, the greater the potential environmental saving from changing to a more fuel-efficient model."

How to get better gas mileage with the car you already have: