Petrol or diesel — here's how to choose
You need a new car, but how do you decide which fuel type to choose? With AutoUncle's guide, you're one step closer to making the right choice.
Your driving patterns and expected annual mileage are the cornerstones of choosing between a petrol and a diesel car. If you make many short trips with a cold engine, you should avoid modern diesel cars, as the injection system and particulate filters can be at risk of failing. Diesel cars need to reach operating temperature regularly so they can regenerate the particulate filter and prevent it from clogging.
As a rule of thumb, it pays to buy a diesel car over a petrol car if your annual mileage exceeds 25,000 kilometres. Previously, the threshold for choosing diesel over petrol was around 20,000 km per year, but technological advances have made petrol cars more efficient. So you should be driving 25,000 km per year or more before it truly makes a difference to go diesel.
Diesel cars are more expensive to buy
Another factor to consider as a buyer is the purchase price and the size of the annual vehicle tax. Diesel cars are typically more expensive to buy, and that premium should naturally be factored into the total cost of ownership. This cost is hard to pin down until you've sold the car and know the actual depreciation over your ownership period.
It's more concrete to look at the vehicle tax: a diesel car needs to be significantly more fuel-efficient than a comparable petrol model to cost the same in annual tax. If you're not aware of this, you can erode the advantage of diesel cars being cheaper to fuel per kilometre. If you're looking at an older car, also be aware that diesel cars without a particulate filter may be subject to an additional surcharge on top of the standard vehicle tax.