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Choosing Between Petrol Or Diesel

Choosing Between Petrol Or Diesel


Choosing between petrol or diesel for your next car used to be a simple choice; read about the pros and cons of each to help decide which is best for you

Choosing between petrol or diesel for your next car used to be a simple choice.

For a small car typically driven on short, town journeys a petrol engine was fine, for a bigger, heavier one then a modern diesel ticked the box.

Today though the picture is changing, and rapidly.

Diesel is now seen as the enemy as studies say it is responsible for tens of thousands of premature deaths from the nitrogen dioxide they emit and there is a growing momentum from the medical profession, legislators and politicians to dramatically curb their use through increasing the tax on them.

In fairness to the motor trade this attack on diesel is a relatively new development and it has not yet had time to respond. Getting on for 20 years ago it was forced to develop diesel as an antidote to the CO2 `greenhouse gas’ pumped out by petrol cars and they have poured billions of pounds into developing the excellent diesels we use today.

However, while it is far too soon to be writing the obituary for diesel it seems almost inevitable that they will be targeted by tax and we will soon see a huge increase in the number of petrol/electric hybrids taking their place.

There is evidence that this has already started. In January 2017 the market for hybrids and electric cars saw a year-on-year rise of 20 per cent to take four per cent of the new car market, one in every 25, as they find growing popularity among tax-conscious business drivers. Registration of new petrol cars rose nine per cent but those for diesel dropped by four per cent.

Here we can look at some of the issues to help you decide, starting with the different characteristics.


In simplistic terms if you drive a big and heavy car a diesel will be better.  Diesels generally produce more of what is called torque, basically power from lower revs, which is better for heavier vehicles and usually gives a more relaxed drive at motorway speeds.

As an example, Bentley’s Bentayga is not only the Crewe company’s first ever SUV but also its first car to have the option of a diesel with its Audi-sourced 4.0 V8.

For a little supermini, such as a Citroen C1, which typically will be used mainly around town there may not even be a choice and it will be a petrol engine or nothing. With these little cars having an official average fuel consumption of almost 70 mpg anyway the fuel-sipping nature of a diesel doesn’t really come into play.


You need to be doing quite high mileage to recoup the higher purchase costs of a diesel as they tend to be a bit more to buy thanks mainly to the technology and the development costs of the latest ones.

Fiat Tipo hatchback in GreyThis will almost certainly become even more relevant as the likely tax onslaught on diesels starts to bite.

Take the new Fiat Tipo for example. The entry level petrol version costs £13,145 and the equivalent diesel £15,145, a gap of £2,000.

True, the diesel’s average consumption is 76 mpg and the petrol’s a third less at 50 but look at the price you pay at the pumps. Diesel is a fraction more expensive at a national average of 122 pence per litre, petrol 120 ppl but even with the better economy it will take

It takes about 30,000 miles to save £1,000 in the better fuel economy.

However, because our car tax system is currently based on CO2 emissions and diesels are better at this than petrol cars, they are taxed less. For now!


Red SEAT Ateca on the roadMany engineers will tell you that diesels have probably reached their peak of development and it will become ever more expensive to get ever smaller improvements. There is greater scope to improve the efficiency in petrol engines and convert more of the energy in a gallon of fuel into usable power and using less in the process.

Some car makers are ahead of the curve and there is a growing number of excellent, very small but ultra efficient turbocharged petrol engines, usually about 1.0 or 1.2 litres. These deliver the best of all worlds; petrol performance and response but fuel economy approaching that of a comparable diesel and with very low emissions.

It seems impossible that such tiny engines can power bigger cars but SEAT and VW, for example, do very well with their 1.0 TSI. Try one in say, the SEAT Ateca SUV and you will be amazed by how well it drives.

There is still mileage – forgive the pun – in small, modern diesels which give some extraordinary fuel economy with 60 to 70 mpg being quite achievable. Given that the pollution problem is mainly about urban air quality, these cars will still find a ready market among those who live in more rural areas.

But to those looking a few years ahead, hybrids probably seem the best route to go down. The technology is still pretty much in its infancy but getting better, cheaper and with increasing range in electric-only mode with every new model.


Diesel is not dead – yet. Modern engines are efficient and their pollution is falling all the time. It is mainly the older ones which are doing the damage and if, as the industry hopes, vehicles are taxed on emissions rather than politicians forcing a blanket tax on all diesel, regardless of their output, then the outlook is not as dire as some predict.

But look at the growth of hybrids and it is not hard to see which way the wind is blowing.

Let us know what you think by commenting below.