Diesel vs petrol car – how to choose which is best

The Automobile Association (AA) says that when buying a new, or second-hand vehicle, one consideration may be whether to buy a petrol or diesel motor. There are many factors that will influence this decision, not least of which is the fuel price.

Despite the fact that petrol is the more expensive fuel option, South Africans still seem to prefer it over diesel. There are many reasons for this, including that diesel vehicles are perceived to be slow, noisy and dirty. In most cases this couldn’t be further from the truth though.

Thanks to advances in engine technology, and the introduction of low sulphur diesel, today’s diesel vehicles no longer the smoke, and they run very quietly too.

There are, however, many other points to consider before you make your final decision. We unpack the diesel vs petrol question.

Fuel efficiency

One of the main motivations for buying a diesel vehicle is its fuel efficiency. On average, diesel engines consume between 25% and 30% less fuel than their petrol counterparts. This means fewer trips to the fuel pump and because diesel is cheaper than petrol, you will probably save quite a bit of money.

Diesel power is a good option if you regularly cover a high mileage and mostly use the highway. However, if the bulk of your driving consists of short trips in and around town and frequent stopping and starting, you’re probably better off with a petrol engine.

Verdict: Diesel is more fuel efficient over longer distances, while petrol is better for short trips and stop-go driving.


Because diesel engines don’t have spark plugs or distributors and therefore less moving parts, they require less maintenance and tend to have a longer lifespan. However, you will have to make sure that oil and filters are changed regularly. If not, the engine could suffer severe damage requiring expensive repairs.

And while you no longer need to bleed excess water out of diesel systems, thanks to cleaner diesel fuels, many vehicles still have water separators that need to be emptied manually.

Another factor to bear in mind is that services on a diesel vehicle are generally more expensive than that of a petrol model.

Verdict: Petrol engines are cheaper to maintain and repair but diesels last longer.

Engine power and performance

It is a fact that diesel engines produce more low-end torque and are therefore more powerful. This makes them ideal towing vehicles or for hauling heavy items.

On the flipside, increased torque means less horsepower. This basically means that diesel vehicles aren’t particularly nippy so if you want a little bit more speed, petrol is probably a better choice.

Verdict: Diesel vehicles have more low-speed torque so they boast better overtaking power and towing ability.

Noise and ride quality

Diesel powered vehicles are no longer the noisy, smelly beasts they once were. There have been vast improvements in technology and production methods which have seen them become quieter and capable of a smoother ride.

However, in some cases, petrol engines are still quieter, smoother and more refined, so the question really is if you are prepared to live with a bit more noise.

Verdict: Petrol engines still tend to be more refined.

Pollution and emissions

Ever been stuck behind a bus or truck? Then you’ll be all too familiar with the unpleasant smell and the clouds of smoke coming from its exhaust.

Fortunately, modern diesel vehicles run much more cleanly than they did before. And because of stricter requirements and the advent of catalytic converters, emissions have dropped considerably.

The burning of diesel fuel still causes more visible pollution than petrol though, even if carbon emissions are lower though so it’s a trade-off between the two.

Verdict: A diesel engine’s CO2 emissions are 20% lower than that of a petrol.

Purchase price

Diesel cars are more expensive than petrol models. However, if you keep your diesel for long enough, you can recoup most of this extra cost at the fuel pump.

You probably will be able to drive it for a very long time as diesel engines generally last longer. Of course this increases its resale value too, provided that you were not lax with the maintenance required.

Verdict: Petrol vehicles are cheaper to buy and maintain but don’t last as long.

In conclusion

In the end, though, it’s all about personal preference and what the intended use of the vehicle is.

If you plan on taking extended road trips around our beautiful country and value fuel efficiency, then diesel is the way to go. If, however, performance is what sets your heart racing you should probably go the petrol route.

This article features on the Automobile Association’s website, here

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Diesel vs petrol car – how to choose which is best