When deciding between buying a petrol or diesel car, there are several factors to consider, including price, running costs, resale price and environmental costs.
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.
The petrol vs diesel decision is a particularly difficult one because there is no easy answer or perfect solution for everyone.
The purchase price of diesel vs petrol car
Although there are several distinctions between a petrol and diesel car, the first major one is that diesel cars tend to be more expensive off the showroom floor.
For comparison purposes, BusinessTech looked at a brand-new Hyundai Tucson – which comes in both a petrol and diesel variant, the 2.0 Elite and the 2.0D Elite, respectively. The diesel variant costs R65,000 more than its petrol counterpart, and while this price difference may vary depending on the car you choose to consider, the diesel variant is likely to always be more expensive.
Despite being more expensive, when it comes to fuel efficiency, diesel cars generally have better mileage than petrol cars. This is because diesel fuel has a higher energy density than petrol, which means that a litre of diesel can go further than a litre of petrol.
According to the Automobile Association (AA), on average, diesel engines consume between 25% and 30% less fuel than their petrol counterparts.
Historically, while diesel cars tend to be more expensive, many motorists justified the purchase because it is more fuel efficient and cheaper than petrol at the pumps.
However, the equation has changed dramatically recently with the wild fluctuations in the price of crude oil, a weakening rand, and rising fuel prices – which has now put a litre of diesel on par with that of petrol, if not more expensive, making it harder to justify the extra cost of a diesel car.
For example, the petrol-engined Hyundai Tucson 2.0 Elite uses 8.9 L/100km, whilst the diesel-engined Tucson 2.0D Elite uses 7.4 L/100km.
If you drive a petrol car an average of 14,000 km per year, you’ll need 1,246 litres of petrol at R22.95 per litre with a total fuel cost of R28,595.
If you have the equivalent diesel car, you will need 1,036 litres of fuel at R21.72 per litre, costing R22,501 in total, saving only R6,094 per year.
But keep in mind that if your diesel car costs an extra R65,000 and your fuel cost savings are R6,473 per year, from greater fuel economy, it would take 10 years to repay the extra cost of the vehicle. Again, this will differ depending on your chosen car, so diligent research is important.
Resale price comparison
Another aspect of this decision is resale value since many of us like to sell our cars later to afford a new one. And historically, a second-hand car will hold its value better if it has a diesel engine. A 4-year-old Hyundai Tucson 2.0D Elite is worth R45,000 more than the equivalent petrol model, but remember that it did cost more in the first place.
Trade-in and retail prices of used cars vary by manufacturer and by who is selling the car, so this is an area you will need to research carefully if resale value is going to be a factor in your decision.
The Environmental Impact of Diesel and Petrol Cars
Historically, diesel cars were known to emit more nitrogen oxides (NOx) and particulate matter (PM) than petrol cars – contributing to air pollution and negatively affecting human health.
However, Suzuki Auto South Africa noted that modern diesel cars have highly efficient filters that capture these particles. A study by the University of Montreal showed that petrol cars emitted up to 62 times more lung-damaging pollution in cold weather than their diesel counterparts.
Suzuki Auto also provided the main points of contention between diesel and petrol cars, which are given in the table below.
In recent years, hybrid vehicles have been gaining popularity and are becoming more affordable. Several vehicle manufacturers offer hybrid options – including Honda, Toyota, BMW, Volvo, and Haval, to name a few.
They produce significantly reduced emissions and have a much lower fuel consumption than petrol and diesel cars – making them worth considering for those who can afford the option.
For comparison, one can buy several petrol-electric hybrid cars in South Africa right now for the same price as or cheaper than the Hyundai Tucson Elite. Some of these options are listed below.
Toyota RAV4 2.5 Hybrid GX-R E-Four
- Price: R698,700
- Fuel consumption: 4.8 L/100km
Haval H6 1.5T HEV Ultra Luxury
- Price: R669,950
- Fuel consumption: 5.2 L/100km
Toyota Corolla hatch 1.8 Hybrid XR
- Price: R539,000
- Fuel consumption: 4.0 L/100km
Honda Fit Hybrid
- Price: R509,600
- Fuel consumption: 3.7 L/100km
Toyota Corolla Cross 1.8 Hybrid XR
- Price: R480,200
- Fuel consumption: 4.3 L/100km