Petrol or diesel – which car is best?

Diesel or petrol, that’s the question. New cars are pretty expensive items with popular cars like the Toyota Corolla starting at R230,500.

You want to get the best value whenever you buy a car and one of the choices you need to make is between a petrol and a diesel engine in your new vehicle.

You’ll need to weigh up various factors including purchase price, running costs, resale price and environmental costs. And that’s not to mention all the additional things you need to consider when buying a vehicle, like make, model, colour, and even parking and car insurance issues!

The petrol vs. diesel decision is a particularly difficult one because there is no easy answer or perfect solution for everyone.

Purchase Price of Diesel Vs. Petrol Cars

Your initial decision might be influenced by how much you’re likely to pay for your car at the outset. A diesel base model Toyota Corolla costs on average R30,000 more than the same model with a petrol engine.

This means that if you’re buying a diesel because of its lower running costs then you have to save R30,000 to make any savings in the long run.

Read: Driving electric vs petrol cars in South Africa

Running Costs of Diesel and Petrol Cars

When it comes to running costs, the most fuel efficient cars on the market have diesel engines. That means that diesel cars have lower running costs because their fuel is cheaper and the car uses less fuel over any journey than an equivalent car with a petrol engine.

A diesel car uses fuel that is more than 10% cheaper per litre and uses about three quarters of the fuel per journey. For example the petrol-engined Toyota Corolla 1.3 uses 6 litres/100 km whilst the diesel-engined Toyota Corolla D 1.4 uses 4.5 litres/100 km.

If you drive a petrol car an average of 14,000 km per year then you’ll need 840 litres of petrol at R12.09 per litre with a total fuel cost of R10,155. If you have the equivalent diesel car you will need 630 litres of fuel at R10.5 per litre costing R6,615 in total, giving you savings of R3,540 per year.

But keep in mind that if your diesel car costs an extra R30,000 and your fuel costs are 3,540 per year less the fuel savings from lower diesel prices and greater fuel economy it would take 8.5 years to repay the extra cost of the vehicle.

Resale Price Comparison

Another aspect of this decision is resale value, since many of us like to sell our cars later in order to afford a new one. And historically, a second hand car will hold its value better if it has a diesel engine. A 5-year old Toyota Corolla 1.9D is worth R20,000 more than the equivalent petrol model, a 5 year-old Toyota Corolla 1.8, but remember that it did cost more in the first place!

Trade in and retail prices of used cars vary by manufacturer, so this is an area you will need to research carefully if resale value is going to be a factor in your decision.

The general perception is that diesel engines last longer than petrol ones, but cars have many other components that are expensive to replace not just the engine itself, so it’s not necessarily true that your diesel car will last longer than an equivalent petrol car. That just depends on what goes wrong with your car!

The current VW scandal may also affect prices. The long term effects of the 2015 Volkswagen emission fixing scandal are still unknown, of course, but this scandal may well have an effect on diesel prices particularly.

The resale value of any used diesel vehicle may well fall, while the difference between petrol and diesel models’ trade-in prices may also narrow, though this remains to be seen.

The Environmental Impact of Diesel and Petrol Cars

Cars with diesel engines use less fuel over every kilometre, so they emit less carbon dioxide, which is largely responsible for global warming, meaning that you may think a diesel is better for the environment.

Life isn’t that simple though. Diesel engines run at higher temperatures, so they emit more nitrogen oxides which are toxic and help form acid rain and smog. This is a problem even with a catalyst because the catalyst only works once it is hot. If you use a diesel car mostly for short journeys then the catalyst never gets up to its operating temperature, so can’t properly filter out these nitrogen oxides.

Soot is another problem with diesels. Diesels emit very small carbon particles (around 10 microns across) called PM10 soot particles. These lodge in our lungs and cause lung cancer, making diesel cars a possible environmental health hazard too.

Additional Factors

Diesel engines are heavier than petrol ones of similar size and turbo-diesels especially develop lots of torque at low engine speeds. What does that mean for you? If you want to tow a trailer or caravan then a turbo-diesel car will be able to pull a heavier weight than the equivalent petrol-engined model.

Though the choice does depend on your driving needs and finances, in general it’s best to forget the diesel and put up with the higher cost of fuel every week. A petrol engine is the best choice for most drivers in South Africa.

In December the price of a lire of petrol was R12.09 versus R10.81 for diesel. However, in January, the energy department announced a 78 cents drop in the diesel price.

Petrol driven vehicles still command a massive market share in SA, close to 80%.

The original article can be found here at

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Petrol or diesel – which car is best?