Is diesel cheaper than petrol per kilometre?

Diesel engines are typically 20-30% more fuel-efficient than equivalent petrol engines, which often makes them cheaper per kilometre despite diesel fuel costing slightly more at the pump. For high-mileage drivers covering 20,000 km or more per year, diesel usually wins on running costs.

Are diesel cars harder to maintain?

Diesel engines have more complex fuel injection and exhaust treatment systems (like DPF filters), which can make servicing more expensive. However, they tend to be more durable and last longer. Maintenance costs are higher per service but may balance out over the vehicle's lifetime if you drive long distances.

Should I buy a diesel car for city driving?

Generally, no. Diesel engines perform best on motorways and long-distance driving where they can reach peak efficiency. Short city trips don't allow the engine to warm up fully and can clog the diesel particulate filter (DPF), leading to costly repairs. Petrol or hybrid is usually a better choice for city-only driving.

Diesel vs Petrol: Which Is Better for Your Car?

Choosing between diesel and petrol is one of the biggest decisions when buying a car. Both fuel types have clear strengths and weaknesses, and the right choice depends on how you drive, how far you drive, and what you prioritise. This guide breaks down the key differences to help you decide.

Fuel Efficiency and Cost per Kilometre

Diesel engines are inherently more efficient than petrol engines. Thanks to higher compression ratios and greater energy density in diesel fuel, a diesel car typically uses 20-30% less fuel per 100 km than a comparable petrol model. For example, a mid-size SUV might use 6.5 L/100 km on diesel versus 8.5 L/100 km on petrol.

However, diesel fuel often costs more per litre than unleaded petrol. In Australia, the gap is usually 5-15 cents per litre, while in the UK it can be 5-10 pence. Use Benzio to compare current diesel and unleaded prices in your area. Despite the higher pump price, diesel's superior economy means it's usually cheaper per kilometre for drivers covering more than 15,000 km per year.

Performance and Driving Feel

Diesel engines produce more torque at lower RPMs, making them feel strong and responsive for overtaking and towing. This is why they're popular in SUVs, utes, and larger vehicles across Australia and New Zealand. Petrol engines, on the other hand, tend to rev more freely and feel smoother at higher speeds. For spirited driving or smaller cars, petrol generally provides a more enjoyable experience.

In the UK, diesel has traditionally been the default for motorway commuters covering long distances on the M1 or M25. If you regularly drive between London and Manchester or Birmingham, diesel's motorway efficiency advantage is significant.

Maintenance and Reliability

Diesel engines are mechanically robust and tend to last longer than petrol equivalents — it's not uncommon to see diesel engines run well past 300,000 km. However, modern diesel cars have complex emissions systems including diesel particulate filters (DPFs) and AdBlue injection that add to servicing costs.

Petrol cars are simpler and cheaper to service. Oil changes, spark plug replacements, and general maintenance are typically less expensive. If you do mostly short trips around Sydney or Auckland, a petrol engine will be less prone to the DPF clogging issues that plague diesel cars in stop-start traffic.

Resale Value and Market Trends

Diesel SUVs and utes hold their value well in Australia and New Zealand, where they're popular for towing and off-road use. Models like the Toyota HiLux, Ford Ranger, and Mitsubishi Triton remain in high demand on the used market.

In the UK and Ireland, diesel resale values have softened due to clean air zones in cities like London, Birmingham, and Dublin. If you plan to sell within 3-5 years and drive mainly in urban areas, petrol or hybrid may hold its value better in those markets.

When Does Diesel Make Financial Sense?

As a general rule, diesel pays for itself when you drive more than 20,000 km per year, do mostly motorway or regional driving, or need a vehicle for towing. If you drive under 15,000 km per year and mostly in the city, petrol is almost always the better financial choice. For those in between, use Benzio to track diesel and petrol prices in your area and calculate your actual cost difference based on your annual mileage.