The pros and cons of petrol and diesel cars

"Should I buy a petrol or diesel?" is a common question we get asked at the NRMA. Your choice should factor in what you will be using the car for, your budget and what your personal circumstances are.

To help wade through all the confusion, we've put together a list of pros and cons for diesel fuel, which covers factors including environment, running costs and intended use.

Pros of buying a diesel car

• Diesels are more fuel efficient than petrol engines and emit less CO2, which makes them better for the environment.

• Diesels produce considerably more torque (pulling power) than their petrol counterparts, which makes them good engines for towing or carrying heavy loads – ie: seven occupants – on a regular basis.

• Due to diesel engines' increased fuel economy, you can get up to double the kilometres out of a tank, meaning less trips to the service station.

• Diesel fuel is less prone to price fluctuations than petrol.

• Some diesels are even more economical than hybrids and are cheaper to buy.

• Diesel engines are generally more rugged than petrol engines, as they have to withstand higher compression ratios; this means better longevity. Mercedes-Benz holds the longevity record, with several vehicles clocking more than 900,000 miles (1.45 million kilometres!) on their original engine. Due to their perceived 'toughness', resale values are usually better for diesels than their petrol equivalents.

• Diesel engines don't have as many parts as petrol engines. They don't require tuning or sparkplugs.

• Diesels are great on the highway, as they provide strong overtaking power and can often do so without changing down gears.

Cons of buying a diesel car

• Regular unleaded fuel is cheaper at the pump than diesel, in comparison to petrol, diesel prices aren't cheap.

• Diesel models can be anywhere from 10-15 per cent more expensive than their petrol counterparts. It is important to work out how many years it will take to recoup the initial outlay (depending on the price of diesel and the kilometres you are driving)

• Diesel engines can be more expensive to service, with their fuel system components often costing many times more than the equivalent part for a petrol engine.

• Diesel uses a particulate filter (DPF) to remove the nasty nitrogen dioxide particles from polluting the atmosphere, however, these can become clogged when used for mainly urban driving which can lead to harmful gases polluting the atmosphere. A DPF is also expensive to replace, running up to $8000 for some models!

• Used diesel cars, unless properly serviced and maintained, can attract much higher repair costs than used petrol cars.

• If you mainly drive in town, you won't see the fuel benefits in smaller sized diesel cars.

• While diesel engines are getting more refined, some still sound like trucks.

• Some service stations still have diesel bowsers away from the main court and not under cover.

Verdict

Newer diesels contain particulate filters that are supposed to catch the nasty particles of nitrogen dioxide which has been linked to cardiovascular and respiratory disease. A 2018 report by The World Health Organisation stated ambient (outdoor) air pollution in both city and country areas causes up to 4.2 million premature deaths worldwide each year. Be sure to check your car's figures (if buying new) and the condition of the filter (if buying used).

When you look at the pros and cons of buying a diesel car, there's no simple way to determine which is better as it really depends on your personal circumstance and how you plan to use the vehicle. There are however, a few things to consider. If you have a large family and will be transporting heavy loads or potentially towing a trailer, small caravan etc. often, then a diesel is the pick.

If, however, you're wanting a small runabout or car to travel around the urban environment, then do the maths before making a final decision. And whatever car you drive, make sure you download the My NRMA app so you can keep an eye on the cheapest diesel and best diesel prices in your area. Plus, you can save up to 5 cents per litre on Premium fuels and 3 cents per litre on regular fuels at participating Ampol service stations.

Consider an electric car

With the emergence of the electric car – and an ever-growing charging network – in Australia, motorists are no longer limited to just diesel or petrol when weighing up their options. Our EV buying guide could be useful to understand your options.