RAC Cars News


Petrol cars vs diesel cars

By raccars Published

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There are a number of reasons as to why people choose a petrol or diesel car, including the difference in running costs and driving style. However these days the arrival of electric powertrains has thrown a spanner into the works by adding yet another element of choice. Nonetheless petrol and diesel engines still make up the vast majority of new car sales so it's best to be clear how the different fuels will affect ownership.

In the past, diesel cars were not particularly popular in the UK because they were considered noisy, dirty and rather unsophisticated compared to petrol engines. However, in some ways they offer a more relaxing driving style, with more torque on tap than petrol cars and lower running costs.

Diesel technology has developed enormously over the last couple of decades and modern diesel cars are far quieter and smoother than they used to be. In some cases, they are also cleaner and greener than their petrol counterparts. Last year's VW Group diesel scandal has tarnished diesel's image somewhat but your choice should be determined by your personal requirements rather than media scaremongering.

Petrol cars vs diesel cars on performance

Basic versions of modern diesel engines probably still register a little higher on the decibel scale than their petrol counterparts, particularly if you put your foot down hard, but there's no longer a major difference in overall refinement. What you are more likely to notice is that diesel cars offer superior power delivery in the lower rev ranges and more torque flexibility. This means that you often have easier access to sufficient power without the need to change gear in order to accomplish manoeuvres that in a petrol car would see you changing up or down.

Petrol engines tend to respond better to a heavy foot. If you want to get the best out of a petrol engine, you need to make it work. This can be a more entertaining driving experience for an enthusiastic driver who enjoys the traditional manual gearbox and the throb of a high revving engine. Modern petrol engines, however, are increasingly assisted by a turbo, which improves power delivery in the lower ranges in the style of a diesel engine. As a result, the gap in performance between the cars is narrowing.

If you spend most of your driving time cruising along the motorway then diesel is usually the best choice. Similarly, if you regularly tow or pull heavy loads then the extra low down torque of a diesel can be useful. Modern diesel cars are often sufficiently tuned to match a petrol engine's performance on a twisty country road too, but you do have to face a growing bias against diesel and the possibility of extra congestion and parking charges in certain locations.

Ownership costs

Diesel cars are almost always more expensive to buy and to repair than their petrol equivalents. However the theory is that you are likely to spend less on fuel over the course of ownership and many car finance deals factor this into the overall equation.

While petrol tends to cost less per litre than diesel, you will use more of it. The differential only really comes into play if you are covering high mileage. Those who complete 10,000 miles or less year are unlikely to notice any significant cost savings from a diesel over the course of a few years once you factor in the higher purchase price.

Diesel and the environment

Emissions are a complex area. While diesel cars emit less CO2 than petrol cars, they make up for that with additional nitrous oxides and nasty particulates which are linked to a number of health problems. Ultimately, manufacturers have invested huge resources into cleaning up diesel engines and the newest petrol and diesel engines are on a fairly even footing.

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