Diesel vs Petrol

What’s best for your budget?

For many years, it’s been assumed that diesel is a cheaper option in the long term. Despite the fact that the initial cost to buy a car might be higher, you’d make your money back in fuel savings.


Is this still true?

Filling up a car, money in handDiesel’s been in the news a lot recently, getting a lot of bad press about emissions and pollution. So much so that the London Borough of Islington has implemented a £96 parking surcharge for diesel vehicles. One of the perks of diesel in the past was lower “road tax” (vehicle excise duty), based on its green credentials in comparison to petrol.

This is all part of a bit of a fight between the industry and the regulators – with regulators saying that the idea that diesel is greener than petrol has always been wrong, due to levels of NOx and harmful particles, and that urban regions in particular are suffering heavily from automotive pollution. The industry has countered that the impact of diesel has been overblown, and that the automotive industry has already implemented more changes to meet environmental regulations than most other industries. They cite the likes of coal power plants as producing more pollution than diesel cars, while the green lobbyists argue that pollution from cars is more concentrated and closer to pedestrians.

Whatever your views on the environmental impact of diesel, there’s no denying that the argument has the potential to change the associated running costs.

As a general rule, diesel cars are more expensive upfront (there are exceptions to this though, so it’s worth shopping around). The cost of diesel at the pump is usually a few pence higher per litre as well – as of Sunday 10th May Petrolprices.com were displaying these average prices:

PetrolPrices May 2015


However most diesel drivers accept these additional costs because they will achieve long term savings in ownership. A tank of diesel can last 25% longer than a tank of petrol, outweighing the initial added expense.


Should you buy diesel?

It’s worth noting that these long term savings are not necessarily achievable by all drivers – if you only drive short distances and your annual mileage is low, you probably won’t make your money back on fuel. It varies depending on initial car costs, and other running costs, but in general if you drive over 10,000 by making long journeys miles a year you could aim to make savings compared to running a petrol car. (You need to be driving long distances to make savings, as the car needs to heat up to get the best efficiency).

Fuel price isn’t all you need to consider though – always research insurance prices and tax bands before deciding on a car. As mentioned, diesel has benefitted from lower tax and other incentives in the past, but if this changes due to environmental pressure (or additional costs such as parking charges or congestion charges come into play just for diesel) will this outweigh your other savings?

You should also think about costs such as upkeep – some believe diesel cars can be costlier than petrol when it comes to repairs and maintenance because there’s more that can go wrong. Newer diesel cars have particulate filters, for example, which can get clogged. The most recent models also have Adblue® tanks and you’ll need to ensure your Adblue® is topped up.

Your decision should also depend on your personal budget – there’s no right or wrong answer. If you want to spend less upfront, either because you’re paying cash or you don’t want to borrow too much on finance, then you might find that petrol gives you a better deal.

To find out about making your diesel fuel last longer, read up on Redex.