Petrol vs Diesel Running Costs
With fluctuating fuel prices and expanding Clean Air Zones, the "best" fuel type is no longer a simple choice.
The Changing Landscape
For decades, diesel was the default choice for UK drivers covering high mileage. However, the combination of "Dieselgate," the introduction of the London ULEZ (Ultra Low Emission Zone), and the rising cost of complex exhaust treatments like AdBlue has shifted the balance.
Fuel Efficiency & Pump Prices
While petrol is generally 2p–5p cheaper per litre at the pump, diesel remains roughly 20-25% more fuel-efficient.
Average Cost per 100 Miles (2024)
- Petrol (approx. 40 MPG): £14.50 – £16.00
- Diesel (approx. 55 MPG): £13.00 – £14.50
- The "break-even" point: You typically need to drive more than 12,000 miles a year for the fuel savings of a diesel to outweigh its higher purchase price.
Maintenance: The Hidden Costs
Modern diesel cars are equipped with complex systems to reduce emissions. If you only drive short city trips, these systems can fail spectacularly.
- DPF (Diesel Particulate Filter): Needs long motorway runs to "regenerate." A blocked filter can cost £500 – £1,500 to replace.
- AdBlue: Most diesels built after 2015 require this urea-based fluid. Expect to pay £1.50 – £2.00 per 1,000 miles.
- Turbochargers: Diesel engines operate at higher pressures, which can lead to more frequent turbo wear on older vehicles.
ULEZ and Clean Air Zones (CAZ)
This is the single biggest factor for many UK buyers today.
Petrol Compliance
Most petrol cars registered after January 2006 (Euro 4) are ULEZ compliant and do not pay the daily charge.
Diesel Compliance
Only diesels registered after September 2015 (Euro 6) are typically compliant. Older diesels face a £12.50 daily charge in London.
Pros and Cons at a Glance
| Fuel Type | Pros | Cons |
|---|---|---|
| Petrol | Cheaper to buy, better for short trips, wider ULEZ compliance. | Lower fuel economy, less "torque" for towing. |
| Diesel | Excellent long-distance MPG, great for towing/heavy loads. | Higher maintenance risk, expensive DPF repairs, AdBlue costs. |
Frequently Asked Questions
Is diesel being banned in the UK?
The sale of new pure-petrol and diesel cars is currently set to be banned from 2035. You will still be able to buy used ones and drive your existing car long after that date.
Which is better for towing a caravan?
Diesel is almost always superior for towing due to its high low-end torque, which helps pull heavy loads from a standstill more easily than a petrol engine.
Buying Used?
Before you choose, check the car"s history to ensure it hasn"t had previous engine or exhaust issues.
Check Vehicle History