Petrol vs diesel vs hybrid vs electric — which used car should you buy?

There is no single best fuel type, only the best fuel type for how you actually drive. Diesel suits high motorway mileage, petrol suits mixed and low-mileage use, full hybrids suit town driving, and electric suits anyone who can charge at home and covers moderate daily miles. Match the car to your annual mileage and journey type before you look at anything else.

Should I buy a petrol or diesel car?

The old rule of thumb still mostly holds: diesel pays off on high, steady mileage, petrol suits everyone else.

• Diesel engines are more efficient at motorway speeds and on long runs. They suit drivers covering 12,000+ miles a year, especially with regular motorway or dual-carriageway journeys. Diesel cars are more expensive to service and repair, and short trips cause specific problems (see below).
• Petrol engines are cheaper to buy, cheaper to service, and cope better with stop-start town driving and short journeys. Fuel economy is lower on long runs, so high-mileage motorway drivers usually spend more at the pump than they would in an equivalent diesel.

If your annual mileage is under about 10,000 miles, or most trips are under a few miles, petrol (or a hybrid) is usually the better choice. Above that, and with mostly longer journeys, diesel starts to make financial sense again.

Why do diesels have DPF problems?

Diesel particulate filters (DPFs) trap soot from the exhaust and burn it off periodically in a process called regeneration. This needs sustained high engine temperature and revs, typically a run of 20 minutes or more at motorway speed. Cars used mainly for short trips never get hot enough for long enough, so the filter clogs.

Warning signs include a DPF warning light, a noticeable loss of power, and the car going into "limp mode". A clogged filter can sometimes be cleared with a deliberate long, fast run, but a badly blocked or damaged DPF needs a garage visit and can cost several hundred pounds to replace.

When buying a used diesel, ask how the car has been driven. A diesel that has spent its life on short urban trips is a higher risk than one that has done regular motorway miles, whatever the mileage on the clock. Check the MOT history for repeat emissions-related advisories or failures, which can point to a DPF problem building up. Our MOT history guide explains how to read that record.

Is a hybrid worth it for short journeys?

Yes, for the right type of hybrid. Full (self-charging) hybrids use their battery and electric motor for low-speed running and regenerative braking, which suits stop-start town driving well. Fuel economy in town can be noticeably better than an equivalent petrol car, with no need to plug in.

Plug-in hybrids (PHEVs) are different. They have a larger battery and a genuine electric-only range, often 20-30 miles when new, but that range only helps if you actually plug in and charge regularly. A PHEV driven mostly on a depleted battery, hauling around the extra weight of an unused battery pack, can return worse real-world fuel economy than a normal hybrid or even a petrol car. Only buy a used PHEV if you have off-street parking or a reliable charging routine, and check the battery's health and remaining range as part of your inspection, alongside the usual checks in our used car buying checklist.

Is a used electric car cheaper to run?

Often yes, but the gap has narrowed. Electricity per mile is normally cheaper than petrol or diesel per mile, especially if you can charge at home on a cheaper overnight tariff, and servicing costs are typically lower because there is no engine oil, filters, cambelt or exhaust to maintain. Battery health is the main used-buying risk: ask for a battery health report or check the manufacturer's app if the seller has access, and expect real-world range to fall gradually with age and mileage.

One thing has changed the calculation: electric cars became liable for Vehicle Excise Duty (VED, or "road tax") from April 2025, ending the previous exemption. Electric cars no longer have a fuel-cost-free tax advantage over petrol and diesel, though they usually still cost less to run overall once fuel and servicing are included. Always check the current VED band for the specific car on GOV.UK, since rates and rules change. Our electric car buying guide covers battery health, charging and range in more depth.

Comparing the four at a glance

How to decide which one suits you

1. Work out your annual mileage and typical journey length. This single factor matters more than brand or badge.
2. Check whether you can charge at home if electric or plug-in hybrid is an option. Without off-street parking, public charging usually costs more and is less convenient.
3. Factor in running costs beyond fuel, including insurance, servicing, and for diesel, the risk of DPF or emissions-related repair bills.
4. Look at total cost over your likely ownership period, not just the purchase price. A cheaper diesel that needs a DPF replacement can end up costing more than a slightly pricier petrol equivalent.
5. Check the specific car's history, not just the fuel type in general. Use the MOT history and, before you commit, a full vehicle history check, as covered in our HPI check vs MOT history guide.

Frequently asked questions

Is diesel worth it for low-mileage driving?

Generally no. Diesel engines and their emissions systems, particularly the DPF, are designed to run hot and hard on longer journeys. A diesel used mainly for short trips under a few miles is more likely to develop DPF and emissions problems than one used on regular longer runs, and you will not recoup diesel's higher purchase and service costs through fuel savings.

Do all hybrids need to be plugged in?

No. Full (self-charging) hybrids never need plugging in; the battery is charged by the engine and by regenerative braking while driving. Only plug-in hybrids (PHEVs) have a plug and a larger battery that needs charging to deliver their fuel-saving benefit.

Will a used electric car cost more to tax now?

Electric cars became liable for Vehicle Excise Duty from April 2025, so they no longer have the tax-free advantage they once had. Check the current VED rate for the specific car's registration date on GOV.UK, since the amount depends on when the car was first registered.

How do I check if a used diesel has had DPF problems?

Look through the car's MOT history for emissions-related advisories or failures, and ask the seller directly about their typical journey types and any dashboard warning lights they have seen. A service history showing a DPF clean, regeneration issue or replacement is also worth asking about directly.

Is petrol always cheaper to run than diesel?

Not always. Diesel typically returns better fuel economy on steady, long-distance driving, which can offset its higher price per litre for high-mileage motorway drivers. For town and mixed driving, or lower annual mileage, petrol usually works out cheaper overall once you include diesel's higher servicing and repair costs.

Compare petrol, diesel, hybrid and electric cars side by side, with MOT history and a market price guide on every listing, on Motofly.