Petrol vs diesel - does it really matter?

When buying a car, one of the first decisions you have to make is if you are going to go for a petrol or diesel car.

There is perhaps no simple answer to this question, as both petrol and diesel cars come with several pros and cons. You may even consider a hybrid car to get the best of both. But, does it really matter which engine you go for?

Broadly speaking, commercial vehicles like trucks or utes use diesel, while family cars rely on petrol engines. However, this is only a simplification, as some family SUVs, like the Mitsubishi ASX, go for a powerful diesel engine.

Below we have gathered some information on fuel efficiency, cost and performance of diesel vehicles vs petrol vehicles.

What is best - diesel engines, petrol engines or hybrid cars?

Hybrid cars use less full and produce less carbon dioxide than petrol or diesel engines. Modern petrol and diesel engines are also cleaner than they have ever been, and have improved fuel economy and emissions.

Diesel vehicles still have the edge when it comes to motorway fuel economy, but they are slowly being overtaken by hybrids. A diesel and petrol vehicle also differs in reliability. Over the years, your diesel vehicle may become less reliable than its petrol counterparts.

Petrol vs Diesel vs Hybrid at a glance

• Hybrid cars are more fuel-efficient when compared to diesel and petrol cars.

• Petrol-hybrid cars are the most reliable fuel type of car.

• Engines using only unleaded petrol may not be as reliable as petrol-hybrid but is more reliable than a diesel engine, especially as the cars age.

• Diesel cars are much more fuel-efficient than petrol.

• New cars using diesel fuel are becoming less popular.

• Diesel emissions used to contribute more to air pollution, but most newer models have been cleaned up.

• Cleaning diesel particulate filters are expensive to replace.

• A diesel-powered car is the main choice for those who require towing abilities, as diesel engines produce a lot more pulling power than a petrol engine.

Differences between diesel and petrol cars

1. Cost

Diesel cars cost more than their petrol counterparts. This is mostly because the cost of registration of a diesel car is more than a petrol car, by about 1 to 3%, depending on the state where the car is purchased.

2. Mileage

A diesel model gets higher mileage than a petrol vehicle. Diesel engines do not require a sport plug and have higher compression, making the engine utilise more fuel. This improved mileage makes up for the extra cost of a diesel car that was initially paid, however, you will have to do quite a bit of driving to recover the extra cost.

3. Fuel price

In Australia, diesel is currently more expensive than petrol. Between October 2021 and January 2023, the average cost of diesel was USD 1.63, whereas petrol averaged at USD 1.19 in Janaury 2023. The extra cost of diesel prices may be mitigated by the higher fuel efficiency of a diesel car.

4. Performance

Diesel engines are more powerful than petrol engines and offer a higher torque (pulling power) and a smoother ride. On the other hand, diesel cars are very noisy and have more vibrations. Petrol cars tend to have less power, however, they are less noisy on the road.

5. Maintenance costs

You will have to fork out a lot more money to maintain a diesel car, as consumables like engine oil and spare parts are a lot more expensive in diesel vehicles. You may make up for these maintenance costs when you sell your car, as diesel cars have a higher resale value. That being said, a petrol engine is much more reliable and have a longer life than diesel engines.

Final Thoughts

There is no real answer to whether petrol or diesel is the right choice for you. Each fuel type comes with its own pros and cons.

Where diesel produces considerably more emissions, they also deliver more power and consume less fuel. A petrol-powered car may not be as fuel-efficient, but they pollute less and are more reliable.

When you are making a choice between the two different fuel types (or considering hybrid or electric), you must consider your finances - now and in the future - what you will need the car for and your driving environment.