Should I buy a used diesel car in 2026?

Diesel cars are no longer the default choice they once were. Electric cars, hybrids and increasingly efficient petrol engines have taken a large share of the market.

But that does not mean you should avoid diesel altogether.

In 2026, diesel makes less sense for some drivers — but for the right type of journey, a good used diesel can still be a very sensible choice. If you fit the diesel niche, you could be onto a great used car for a great price.

Who can still benefit from diesel?

Diesel remains particularly attractive when you regularly cover long distances in a single journey.

For example:

  • A long-distance commuter travelling 40–100+ miles each way.
  • Someone regularly driving hundreds of motorway miles for work.
  • Drivers without reliable access to home or workplace charging.
  • People who need strong motorway fuel economy and long range between refuelling.
  • Buyers wanting a large, comfortable executive car without spending new-car money.

A modern diesel can combine good motorway economy with a relatively large fuel tank, making long journeys straightforward.

What about the cost of diesel?

Owing to the geopolitics of the middle east, both petrol and diesel are expensive right now. Diesel fuel prices have been particularly badly hit. In September 2026, the RAC reported an average UK diesel price of 190.08p per litre, although prices will always fluctuate.

However, price at the pump doesn’t tell the whole story:

Consider a diesel achieving 55mpg:

190p/litre @ 55mpg =16p per mile

A petrol car achieving 40mpg at a typical reduced price

160p/litre ÷ 40mpg ≈ 18p per mile

So an efficient diesel can still have a significant fuel-cost advantage when driven enough.

The used diesel opportunity

There is another reason to consider diesel in 2026: depreciation.

Cars that were expensive and well-equipped when new — particularly executive saloons and estates — can now be surprisingly affordable second-hand.

A well-maintained BMW 3/5 Series, Mercedes-Benz C/E-Class or similar car can offer:

  • Excellent motorway comfort
  • Strong real-world fuel economy
  • High equipment levels
  • Long-distance refinement
  • Much lower purchase prices than when new

But of course, beware that now depreciated luxury cars from the mid 2010s will contain high cost parts, will be out of their manufacturer warranty cover and will naturally carry higher repair costs if and when problems arise.

So, should you buy one?

Consider a used diesel if you:

  • regularly drive long distances
  •  spend substantial time on motorways
  • need long range and quick refuelling
  • have limited charging access
  • can find a well-maintained example at a sensible price
  • have emergency savings to cover repairs

Avoid a used diesel car if you:

  • mainly make short urban journeys
  • rarely cover significant mileage
  • have convenient and cheap home EV charging
  • are buying an old diesel with poor service history
  • have no emergency savings to cover repairs