Diesel is currently 7.9p per litre more expensive than petrol in the UK. But pump price is only part of the story — diesel engines are more efficient, which changes the maths significantly depending on how you drive.
Diesel engines are inherently more thermally efficient than petrol engines. A diesel car typically achieves 15-20% better fuel economy than an equivalent petrol model. For drivers covering more than 12,000 miles per year with significant motorway driving, diesel often works out cheaper overall despite the higher pump price.
| Driver type | Recommendation | Reason |
|---|---|---|
| Mostly city / short trips | Petrol | Diesel needs long runs to warm up properly — city use increases wear |
| Mixed driving | Petrol | Simpler, cheaper to maintain at current price gap |
| High mileage motorway | Diesel | Better mpg offsets higher pump price over distance |
| Van / commercial | Diesel | Torque, efficiency and range suit commercial use |
| Considering EV switch soon | Petrol | No point paying diesel premium if switching in 1-2 years |
Diesel engines have additional components — most notably the Diesel Particulate Filter (DPF). If used predominantly for short city trips, the DPF can become blocked, leading to expensive repairs (£1,000-£3,000). For city drivers, these hidden costs can easily wipe out any fuel saving.
Diesel produces lower CO2 than petrol but higher levels of NOx and particulates — the pollutants most harmful in urban areas. Many UK cities now have Clean Air Zones where older diesel vehicles are charged. Check whether your vehicle is affected before buying diesel.
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