Nowadays most petrol cars beat diesels hands down for overall day-to-day expenses, claims Which? And some diesel models can take 14 years before they recoup their initial higher cost price.
With drivers having to pay a premium for a diesel car – typically £1,000 to £2,000 more on a new car - Which? claims it can take up to 14 years to recoup upfront costs in fuel savings. Lower pump prices for petrol and advances in petrol-engine efficiency mean petrol cars are often the better bet, it says.
Which? tested a range of diesel superminis to estates and 4x4s, looking at identical-spec petrol and derv versions of the Ford Fiesta, Vauxhall Astra, VW Tiguan, VW Sharan, BMW 5 Series, and Peugeot 308 SW. They calculated the annual fuel bill for each based on a mileage of 10,672 (the average annual mileage in the 2012 Which? Car Survey).
"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," Which? says. "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."
Petrol vs dervTake Ford's Fiesta. The £15,594 1.6 diesel Which? tested can, claims Ford, return up to 76.3mpg overall (though Which? recorded a more modest combined 62.8mpg figure), not far off the claimed overall 49.6mpg figure for the petrol model. "This means that the actual fuel economy difference between the diesel and petrol version of the Fiesta is less marked," Which says.
"The upshot is that you'll need to keep the diesel Fiesta for a long time to recoup the premium paid for the car in fuel savings. If you drive mostly in town, the payback period is around four-and- a-half years. But if you're doing an average mix of driving, it will be nearer eight years before you break even."
So, the death of diesel? At one point the government even incentivised diesel ownership with cheap fuel duty. Now, for every litre of diesel sold approximately 80p of it goes to the Government. Times have changed. And the numbers of complaints from drivers with problematic diesel particulate filters (DPFs) - requiring cars to do regular bursts of high speed to burn off soot build-up - are on the rise.
Going diesel, clearly, is not the automatic choice for the cost-conscious driver.
Which? Petrol Fiesta vs Diesel Fiesta