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Vehicles

This or that: Should you buy a petrol or diesel car?

There are a number of crucial differences between driving a petrol or a diesel vehicle, from resale values to servicing costs – here we look at the pros and cons of each.

By Shell on Feb. 15, 2022

A shift to electric power might be the overriding long-term focus of the motoring industry, but in the here and now more Australian buyers are pondering a much more traditional car-ownership question – which is better for me, a petrol or diesel engine?

Each style of engine has different strengths and weaknesses and, consequently, a different type of ideal buyer. To figure out where you fall, you need to think about how the following factors line up with your personal requirements, preferences and budget.

Price and resale

All things being equal, you'll pay more for a diesel, whether by the extra dollars manufacturers tend to charge for the engine option itself or how they structure their model line-ups – some cars, for example, will make an automatic transmission or all-wheel-drive mandatory with the diesel but not the petrol, giving the petrol an even larger price advantage.

By and large, the percentage premium for diesel will be returned when you go to sell or trade up, but depreciation is a complex business and diesel resale differs for different styles of cars. Today's average SUV tends to return similar resale regardless of engine but values of diesel hatches and sedans are softening as diesel becomes a less popular choice in these segments. For something heavy-duty like a 4WD or ute, diesel resale can be much stronger than petrol.

Driveability

A big diesel attraction is its superior low-rev pulling power, or torque, which is why they've historically been the choice for heavy commercial vehicles.

If you regularly tow or carry a full load of passengers, that extra low-rev go will be a desirable asset. Petrol engines, though, rev harder, have a wider useable rev range and today's turbo-petrol models are closer than ever to diesels for economy and low-rev power, which is why they remain the default choice for most cars and mandatory for anything with a sporty streak.

Servicing and ongoing costs

With servicing affordability a key factor in many buyers' purchasing decisions and manufacturers now tending to cap service costs for a certain period, it's not uncommon to pay roughly the same on servicing over that duration regardless of what engine you choose.

But a modern diesel engine is a more complex and finicky beast than your average non-turbo petrol. As well as a turbo being mandatory, it will have a complex high-pressure fuel system and downstream equipment such as a diesel particulate filter (DPF) to clean up its inherently dirtier emissions.

Some brands won't absorb the higher servicing cost of a diesel on their capped-price plans and a diesel can be susceptible to technical issues if it's not driven 'properly'. Only driving a diesel on short stop-start trips is a recipe for DPF failure because they need to reach a certain temperature to burn off the soot that forms inside. Replacement DPFs can cost as much as $7000.

Petrol engines don't have the same short-trip driving worries and also tend to be lighter, so the car doesn't eat through brakes, tyres and other consumables quite as quickly. But today's most advanced petrol engines also now tend to be equipped with a turbo and high-pressure fuel system, just like a diesel. If something significant goes bang post-warranty, you'll be digging deeper into your pockets to put it right than you would with a more basic petrol engine.

Summary

There’s no one-size-fits-all answer to the question of diesel verus petrol. If you’re buying a family car with no plans to tow anything, you may be better off to save money by buying a petrol-engine model at a lower price point. If you’re buying a work ute, you might prefer a diesel option, especially if you plan to trade up in a few years and want to maximise resale value. And if you’re choosing a turbo engine, you’ll probably pay the same in servicing and maintenance costs regardless of whether you opt for petrol or diesel.

Disclaimer

Viva Energy Australia Pty Ltd (“Viva Energy”) has compiled the above article for your general information and to use as a general reference. Whilst all reasonable care has been taken by Viva Energy in compiling this article, Viva Energy does not warrant or represent that the information in the article is free from errors or omissions or is suitable for your intended use.