Petrol vs diesel: which engine should I choose?

Petrol or diesel? Unless you choose an all-electric model such as the Nissan Leaf, it’s a question you’ll have to consider before choosing your next car. But which is the right choice for you?

Petrol or diesel? Unless you've gone all-electric, you'll have to decide which is best before you get your next car.

There’s some misconceptions out there that can trip you up when you’re deciding so, to help you out, here’s our guide to explain what the difference between the two really is, and how they compare on the road.

Petrol and diesel have been around a relatively equal amount of time, but it’s petrol that got ahead when it came to cars. That’s because its higher combustibility leant itself to well… combusting.

Companies like Citroen and Mercedes were developing diesel engines for cars as early as the 1930s, but it wasn’t until after the 1973 oil crisis that manufacturers started to seriously think of the diesel engine as an alternative to petrol.

Misconceptions…

Diesel power used to have a reputation for being a noisy, soot-spewing fuel, but new diesels are as smooth and quiet as their petrol siblings. Some may say that diesel doesn’t offer the performance a petrol can either, but the latest turbocharged technology ensures they are usually as quick – if not quicker – than a similarly sized, naturally aspirated petrol engine.

Traditionally, petrol engines are thought of as less economical than diesels. It’s true that diesel usually offers more miles to the gallon, but these days petrol isn’t that far behind. For example, a 2.0-litre Audi A4 petrol is capable of over 50mpg – a figure a 2.0-litre petrol engine could only have dreamed about a few years ago.

Economy…

It’s true petrol has caught up from a fuel economy perspective, but diesels generally still offer the more impressive mpg stats.We’ve compared petrol and diesel variants of two popular lease cars – the Mercedes C Class and Volkswagen Golf – to show you the exact difference.

 

Mercedes C Class

Volkswagen Golf

petrol

(C200 SE)

47mpg*

 (1.4 TSI)

51.4mpg*

diesel

(C200d SE)

65.7mpg*

 (1.6 TDI)

72.4mpg*

*manufacturer’s stats, combined cycle.

Price wars…

Diesel cars themselves carry a heftier list price than petrol models, but the cost of fuel itself used to dictate which one some people went for. In fact, diesel was designed to offer more mpg and to be cheaper to produce. No such luck for UK motorists however, where diesel drivers have traditionally paid an extra premium for their extra mpg.

The cost of a litre of fuel used to dictate which type people opted for, but diesel prices are now largely in line with petrol.

However, the last few years has seen the price gap shrink considerably and, at the time of writing, diesel and petrol are around the same price. So with ever-closer economy stats and the price gap closing too, the choice looks even harder than ever.

Differences behind the wheel…

Those who love driving may tell you diesel power can never outdo petrol if you want fun behind the wheel. Despite diesel’s immeasurable improvement when it comes to refinement, the lower rev range and diesel soundtrack don’t exactly correlate with petrolhead paradise.

While they miss out on the low-range torque of a diesel, petrol engines are happier to rev and therefore some will find them more enjoyable to drive. There’s no denying the sound from something like Ford’s V8 Mustang is soul-stirring too – not something that can be said about the gruff rumble of most diesels.

The Audi R10 is one of the only diesel-powered racing cars to have competed at Le Mans 24h.

In short, petrol does offer what most consider to be the more engaging drive thanks to its rev-happy nature – just what you want if you enjoy blasting down a twisty lane. Diesels low-down torque on the other hand, makes them fantastic for motorway cruising, but not so much of a B-road blaster.

Which should you choose?

Whether you opt for petrol or diesel, all new engines are relatively equal in terms of refinement, so which one you choose really does depend on the kind of driving you do. If you do more than 15,000 miles a year and travel on motorways a lot, the fuel-saving ability and low-down grunt of a diesel means it’s probably the better choice for you.

Should you choose a petrol or a diesel?

If for the main part however, your commute mainly consists of traffic-packed towns, then it probably won’t be worth paying the premium for a diesel variant. Not only that, petrol engines don’t take as long to get up to temperature as diesels, so are mechanically better suited to shorter trips, too.

Remember, while diesel variants may carry the higher list price,they will also carry the higher residual values. When it comes to leasing then, you may find the car that fits you best is a cheaper proposition than you thought.