Petrol or diesel - which is cheaper? - Which is cheaper?
For example, the diesel Fiat 500 does nearly 14mpg more than the 1.2 petrol, but it costs a massive £2400 more to buy, which means that, using economy figures alone, it would have to cover 133,164 miles before the better economy compensates for the higher price. The diesel’s lower servicing costs narrow the gap, but the petrol still works out £981 cheaper to own over three years/36,000 miles, or £327 cheaper per year.
Going for the diesel version of the Mazda 6 is a no-brainer, however. Even though the 2.2D 163 costs £1100 more than its petrol equivalent, it starts to repay you at the pump after 40,279 miles. Its lower depreciation and road tax figures also mean that the diesel version is £1191 cheaper than the petrol over three years.
Similarly the Peugeot 3008 and Volkswagen Golf diesels are both cheaper over a three-year period than the petrol versions, by £705 and £442, but the BMW 3 Series throws up a bit of a surprise. At three years, the £2100 premium for the 320d diesel over the 320i petrol still isn’t recovered through fuel savings or higher resale values, while road tax is the same and the diesel’s insurance and servicing are more expensive. Overall, the 320i beats the 320d by £709 over a three-year period.
Generally speaking, though, the bigger the car you’re considering, the smaller the premium charged for the diesel, and the more miles you cover, the more likely it is that a diesel will save you money.
To help you calculate which car works out cheapest for you, we’ve posted a tool online at whatcar.com. Simply type ‘petrol or diesel’ into the search box. You can even vary your mileage to see how it affects the decision.