Choosing a petrol vs diesel car

If you are choosing a new car (or even your first car) should you choose petrol or diesel? While petrol is cheaper to buy, diesel cars tend to be more economical. Petrol cars tend to be cheaper whereas diesel cars tend to be a bit more expensive and can cost a little more to maintain. Petrol cars have similar servicing costs to diesel cars, but diesel cars attract a lower tax rate because of the lower CO2 emissions. Insurance costs can vary depending on overall performance and don’t necessarily favour one or the other.

If you do 30,000 miles a diesel engine will save you somewhere in the region of £500, depending on the car and engine size, but with diesel cars often costing £1000-2000 more than their petrol equivalents with the same specification, this means you will have to do a lot of miles to see your savings.

Smaller cars, where the motor is more of a cost in relation to the whole car, tend to use smaller petrol engines because putting a diesel engine in it would increase the price too much. If manufacturers want better economy while maintaining power with petrol engines they can use a turbocharger, supercharger or both.

When driving, diesel cars are more efficient, but they can be noisy. However, modern diesels are very quiet in the cabin; often as quiet as their petrol equivalents. If they are fitted with diesel particulate filters to trap soot particles the better fuel economy can mean less impact on the environment. These particulate filters can get clogged if you only use them for short journeys, and replacing them can be expensive.

If you want to tow a caravan, boat or trailer, diesel is superior. You will need a sizable petrol engine to out-tow a decent diesel engine as diesel engines produce a lot of torque to help get heavy loads moving.

If saving fuel is your primary motivation for purchasing a diesel, check out our tips for driving more economically. Many drivers waste up to 35% more fuel than they need to through bad habits, aggressive driving and lack of anticipation. If you spend £1500 on fuel a year, you could save £500 just by changing your driving style.

Of course, don’t put the wrong type of fuel in your vehicle otherwise you could be up for an expensive repair bill.

Diesel advantages

• Engines usually have more torque and are better for towing and for hilly regions
• Cheaper if you do more miles
• Diesel cars tend to retain their values better than petrol cars
• Diesel is usually a better choice if you are purchasing a large SUV
• Less visits to the service station means less opportunity for impulse chocolate bar purchases!

Petrol advantages

• Cheaper if you do less miles – anything less than around 11000 miles a year and you should buy a petrol car
• Engines tend to be quieter and more refined than diesel engines (although, less so with modern diesels)
• Engines tend to be more reliable and cheaper to maintain
• Petrol is usually a better choice if you are purchasing a smaller car

There’s a useful petrol and diesel cost calculator here.