Petrol or diesel: which should you buy? - So what should you do?

Do your sums before you buy.

Diesel does not have the advantage you might expect. To get the benefits of a diesel you have to drive a lot of miles and own a car for longer.

A diesel car's superior fuel economy is not enough to cancel out the higher initial outlay.

To reap the rewards you need to be doing a lot of miles, have to hang on to your car for at least three years and you have to choose a diesel with a strong resale value.