Petrol vs diesel cars: which is the better choice?

From fuel costs to mileage, we guide you through the petrol vs diesel debate to help you pick the car that best suits your lifestyle.

Petrol and diesel cars are still very much part of the picture. Petrol makes up around 47% of all new-car sales, and diesel remains a solid choice for many drivers in the UK. Both options can be practical and reliable – and this handy guide will help you decide which is best for your next car.

Remember, you can buy a brand new or used car right here on Carwow. And you can sell your car, too. We’re here to help you through every step of your car-changing journey.

What’s the difference between petrol and diesel cars?

So, you’re trying to decide between a petrol or diesel car, but what’s the real difference? Let’s break it down.

1. Purchase price

Diesel cars usually cost a bit more upfront. That’s because diesel engines are built tougher to handle high compression, and they come with extra gadgets such as diesel particulate filters (DPFs) and AdBlue systems to keep emissions in check.

2. Running costs

Diesel cars can cost a little more to insure and service, but they usually make up for it at the pumps. They’re more fuel-efficient, especially on long motorway drives, and that AdBlue top-up is a minor expense every few thousand miles. But whether you actually spend less per mile depends on your driving habits and local fuel prices. Diesels shine on long trips, while petrol cars often make more sense for short city journeys.

3. Emissions and tax

Modern diesels aren’t the pollution villains they once were. Thanks to DPFs and AdBlue, today’s diesels are much cleaner and more efficient than older models. They’re great for long motorway trips, offering strong fuel economy and lower CO2. That’s good news for your road tax or company car tax. But if most of your driving is short city trips, petrol cars usually have the edge for local air quality, since diesels can still release higher levels of nitrogen oxides (NOx) in stop-start conditions. Older diesels are hit hardest, so low-emission zones such as London’s ULEZ can still catch them.

4. Driving and performance

Diesel engines have a bit more “clatter” than petrols, but they’ve come a long way. They rev lower (around 5,000 RPM), but pack serious torque, making them brilliant for towing or long motorway runs. Meanwhile, petrol cars feel zippier at higher revs, which some drivers prefer.

Pros and cons of petrol cars

Petrol cars are popular for city driving and short trips. They’re generally cheaper, smoother, and easier to maintain than diesel cars, but use more fuel and emit more CO2. Here’s a breakdown:

Pros of petrol cars

• Generally cheaper to buy than diesel equivalents.
• Quieter and more refined engines.
• Avoid the complications of diesel particulate filters (DPFs).
• Simpler engines mean lower servicing and repair costs.
• Better MoT pass rates, especially as they age.
• Petrol fuel is often slightly cheaper than diesel.

Cons of petrol cars

• Less fuel-efficient, especially on long motorway drives.
• Have higher CO2 emissions, which can affect their road and company car tax.
• Their lower torque makes them less suited for towing or heavy loads.

Pros and cons of diesel cars

Diesel cars suit high-mileage and motorway drivers but are noisier, less efficient for short trips, and now come in fewer models. Here are some more pros and cons:

Pros of diesel cars

• Excellent fuel efficiency, especially on long-distance drives.
• Longer range between refuelling stops.
• Strong motorway performance and low-rev torque.
• Perfect for towing caravans or heavy loads thanks to its low-rev, high-torque engines.
• Lower CO2 emissions compared with equivalent petrol cars, which can reduce road tax.

Cons of diesel cars

• They’re more expensive than equivalent petrol models.
• Potentially higher servicing and repair costs due to complex engines.
• Older diesels may face charges in low-emission zones (e.g., ULEZ).
• The engine can be noisier, often described as a “clatter”.
• DPFs can clog if the car is mostly used for short, low-speed trips.
• Limited choice of new diesel models compared with petrol or hybrid options.

Should I buy a diesel car or a petrol car?

The short answer is that it depends on how you drive. Diesel suits long motorway trips or heavy loads, while petrol is better for short journeys and city driving. If you live in a city and mostly commute, petrol is usually the more practical and cost‑effective choice.

The 2030 ban on petrol and diesel cars

When deciding between a petrol and diesel car, it’s worth noting that the UK government has reinstated the 2030 target for ending sales of new petrol and diesel cars, with a full ban – including hybrids – set for 2035. After this date, only zero-emission vehicles, such as electric and hydrogen cars, will be sold as new.

The good news is that this restriction applies only to new vehicles; there are currently no limits on buying second-hand petrol and diesel cars. Existing low-emission zones mainly target older vehicles, and it remains unclear whether new emission standards or expanded zones will be introduced in the future.

Petrol vs diesel cars FAQs

Do diesels last longer than petrol?

Generally, yes. Diesel engines are built tougher because they have to handle much higher compression, and they usually run at lower RPMs, which means less wear and tear over time. Diesel fuel also has natural lubricating qualities that help parts last longer. A well-looked-after petrol engine can still rack up plenty of miles, but diesel engines often go far beyond that – many can hit anywhere from 500,000 to 1,000,000 miles if properly maintained.

Is it worth buying a diesel car?

Diesel cars are worth it if you do regular long-distance driving or need strong towing power. But for mostly city driving or low mileage, petrol, hybrid, or electric cars are a better fit.

What happens if you put diesel in a petrol car?

If you put diesel in a petrol car the engine may misfire, smoke, or fail to start because diesel won’t combust properly. If this mistake is made, don’t start the engine and have the tank drained immediately to avoid damage.

What happens if you put petrol in a diesel car?

Putting petrol in a diesel car can damage the engine and fuel system because petrol lacks diesel’s lubrication. If this happens, don’t start the engine and have the car towed for a professional fuel system flush.

Car change? Carwow!

Looking for a new set of wheels? With Carwow you can sell your car quickly and for a fair price – as well as find great offers on your next one. Whether you’re looking to buy a car brand new, are after something used or you want to explore car leasing options, Carwow is your one stop shop for new car deals.

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