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Petrol vs diesel car: which is cheaper to run?

Updated June 2026 8 min read

Quick verdict

Petrol usually suits lower-mileage and city drivers. Diesel can still make sense for high-mileage motorway driving or towing, but the higher purchase price, emissions equipment and clean air zone risk mean it is no longer the default money-saving choice.

Option A

Petrol

Petrol cars usually cost less to buy and suit short trips, city driving and lower annual mileage.

Option B

Diesel

Diesel cars can use less fuel on long motorway runs and towing, but need the right driving pattern to avoid emissions-system problems.

Side-by-side comparison

Diesel engines are efficient on long steady journeys, but they cost more to buy and can be unsuitable for repeated short trips. Petrol cars are usually cheaper upfront and simpler to own for average UK mileage.

Upfront price

Petrol

Usually lowerBetter

Diesel

Usually higher

Fuel economy

Petrol

Lower on long runs

Diesel

Usually better on motorwaysBetter

Short trips

Petrol

Better suitedBetter

Diesel

Can cause DPF issues

Towing

Petrol

Can be less efficient

Diesel

Strong torque helpsBetter

Clean air zone risk

Petrol

Lower for many modern petrolsBetter

Diesel

Higher for older diesels

Best for

Petrol

Low to average mileage

Diesel

High motorway mileage

Pros and cons

Petrol pros and cons

Pros

  • ✓Usually cheaper to buy
  • ✓Good for short trips
  • ✓Simpler emissions systems
  • ✓Lower clean-air-zone risk for many modern cars

Cons

  • -Uses more fuel on long motorway journeys
  • -Can be less efficient for towing
  • -Higher fuel use at very high mileage
  • -May emit more CO2 than equivalent diesel

Diesel pros and cons

Pros

  • ✓Strong fuel economy on long runs
  • ✓Good torque for towing
  • ✓Long range between fill-ups
  • ✓Can suit high annual mileage

Cons

  • -Higher purchase price
  • -DPF and AdBlue systems can add cost
  • -Short trips can cause problems
  • -Older diesels may face city charges

Cost examples

Low-mileage city driver

Petrol usually wins because the diesel fuel saving is small and short trips can create DPF issues.

Mileage
6,000/yr
Likely fit
Petrol

Average mixed driver

At average mileage, diesel may save fuel but often takes many years to recover a higher purchase price.

Mileage
8,500/yr
Likely fit
Petrol

High-mileage motorway driver

Diesel can still make sense when annual mileage is high and journeys are long enough to keep emissions systems healthy.

Mileage
18,000/yr
Likely fit
Diesel

When to choose Petrol

  • ›You drive under about 10,000 to 12,000 miles a year
  • ›Most journeys are short or urban
  • ›You want a lower purchase price
  • ›You want to avoid DPF concerns
  • ›You drive into clean air zones

When to choose Diesel

  • ›You drive high annual motorway mileage
  • ›You regularly tow a caravan or heavy trailer
  • ›You do regular long runs
  • ›The diesel version is not much more expensive
  • ›You are buying a compliant newer diesel and understand local clean air zone rules

Calculator

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Inputs

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FAQs

Does this include tax or ULEZ charges?

No. Add local charges separately when comparing specific cars.

Why use pence per litre?

UK pump prices are usually quoted in pence per litre, so the inputs match common pricing.

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