Diesel cars may not be cheapest for drivers, according to watchdog

DRIVERS who invest in a diesel-engine car may not be saving money in the long run, according to new research by consumer group Which?.

The organisation said the  petrol versions of many cars may be a more economic choice for drivers with a typical annual mileage.

Despite superior fuel economy and usually lower car tax, the Which? investigation found  diesel cars are often more expensive to run than petrol cars.

In tests, the petrol versions of the BMW 5 Series, Vauxhall Astra, Volkwagen Tiguan and Ford Fiesta were all judged  better value than the more  expensive diesel-fuelled models. Diesel versions were deemed to be better value for only two cars – the Peugeot 308SW estate and the MPV Volkswagen Sharan.

The Which? report said diesel only really pays off for people who do a lot of mileage in their cars and that, for drivers who do less than 10,000 miles a year,  petrol is always better value.

Fuel economy tests carried out by Which? also showed cars may use more fuel than manufacturers claim.

The Which? study also considered reliability, taking information directly from a 2012 Which? car survey, which found that petrol cars are generally more reliable than diesels – both in the first three years of their lives, which is typical the  warranty period, and even more so between four and eight years old.

However, motorists still  appear to be choosing diesel cars, believing it will save them money in the long run.

In the first five months of this year, diesel cars accounted for 51 per cent of all new cars – meaning this year is set to be the first in which diesel cars will make up more than half the new-car market.

However, with drivers having to pay a premium for a diesel car – typically £1,000 to £2,000 more for a new car – the tests reveal that it could take up to 14 years to recoup the up-front costs in fuel savings.

And new technology means petrol cars are more efficient than ever before. According to the Which? research, lower pump prices for petrol and advances in petrol-engine  efficiency mean that petrol cars now often provide better value for money.

The report said: “With petrol now around 5.5p a litre cheaper and some makers offering super-economical petrol engines, it is getting harder to justify the price premium.

“We have compared popular models to find out whether diesel is the best choice. The results may surprise you.” Which?  executive director Richard Lloyd said: “Fuel price rises have been hitting household budgets hard, so it’s important that consumers know they are getting value for money when they buy a car.

“Diesel cars are known for their fuel efficiency, but with lower pump prices for petrol and a premium price-tag for  diesel cars, it may make more financial sense for families to go for the petrol version.”