The diesel vs petrol question comes up whenever someone is buying a used car, and the answer has changed significantly in the last decade. Here is a practical guide based on real driving patterns.
The basic economics
Diesel engines are more fuel-efficient on motorways and long runs, producing more miles per gallon than an equivalent petrol engine at sustained speeds. However, diesel cars are typically more expensive to buy and maintain. The fuel economy advantage makes sense only if you cover a significant motorway mileage.
The problem with diesel and short journeys
Modern diesel cars are fitted with DPFs (Diesel Particulate Filters) that need high exhaust temperatures to regenerate. Short urban journeys, commutes under 10 miles, and lots of stop-start driving do not generate enough heat for the DPF to clean itself. The filter blocks, the warning light comes on, and a forced regeneration or DPF clean is needed. This is an ongoing and recurring cost for diesel drivers who mainly drive short distances.
When diesel makes sense
Diesel is the right choice if you regularly cover 15,000 miles or more per year with a significant proportion on motorways or A roads at sustained speeds. The fuel economy advantage is real in those conditions and the DPF will regenerate naturally.
When petrol makes more sense
Petrol makes more sense for: mostly short urban journeys; lower annual mileage (under 12,000 miles per year); drivers who are not confident maintaining the DPF through regular long runs; and those who want lower maintenance complexity.
What about hybrid and electric
Mild hybrids and full hybrids reduce the fuel economy advantage of diesel in urban conditions. For short journeys with access to home charging, a plug-in hybrid or electric vehicle may make more sense than either. For those without home charging, a petrol or mild hybrid petrol remains the practical choice for most shorter-distance drivers.
Whatever you drive, Steins Garage services all fuel types including hybrid vehicles. Call 0131 554 3423 or book a service online.