Diesel vs Petrol

26 Sep 2024 by Sam Bisby
Petrol vs Diesel

Should I get a petrol or a diesel car: this a question that has burned on for quite some time in the motoring domain. 

Today, that question is possibly more pressing than ever, thanks largely to new legislation and the changing views around the cleanness of diesel cars.

To clear some points up, we dig deep into the subject and shed some light on the current debate on whether you should buy a petrol or diesel car.

Difference Between Petrol vs Diesel Explained

While petrol and diesel are both derived from crude oil, their chemical compositions and combustion processes are distinct. Petrol is a lighter hydrocarbon mixture with a higher octane rating. It ignites more easily and burns more completely than diesel, resulting in a cleaner exhaust and better performance in smaller, lighter vehicles. Petrol engines typically have more cylinders and require higher maintenance due to their more complex ignition system.

Diesel fuel, on the other hand, is a heavier, more viscous hydrocarbon blend with a lower cetane number. It requires compression to ignite, producing a slower, more powerful combustion that’s well-suited for larger, heavier vehicles like trucks and SUVs. Diesel engines are generally more fuel-efficient and have fewer moving parts, leading to lower maintenance costs. However, diesel exhaust contains higher levels of particulate matter and nitrogen oxides, which can contribute to air pollution and respiratory health problems.

In recent years, advancements in diesel engine technology have led to a reduction in emissions and improved fuel efficiency. However, the choice between petrol and diesel remains a complex one, influenced by factors such as vehicle type, driving habits, and environmental considerations.

Petrol vs Diesel Cars: What’s Better Today

While diesel engines once dominated the market for their fuel efficiency, the landscape has shifted significantly in recent years. The rise of hybrid and electric vehicles, coupled with stricter emissions regulations, has made petrol cars a more attractive option for many consumers.

Modern petrol engines have become increasingly efficient, thanks to technologies like direct injection and turbocharging.

Additionally, petrol-powered hybrid vehicles offer a balance of performance and fuel economy, making them a compelling choice for those seeking to reduce their carbon footprint.

While diesel engines continue to be popular in certain regions and for heavy-duty applications, petrol cars have emerged as a strong contender in the modern automotive market, offering a combination of efficiency, performance, and environmental friendliness.

Petrol vs Diesel Performance Compared

While diesel engines were once synonymous with torque and power, modern petrol engines have narrowed the gap significantly. Advancements in technology, such as turbocharging and direct injection, have enabled petrol engines to deliver impressive performance.

Petrol cars often boast quicker acceleration and higher rev limits, making them more responsive and exhilarating to drive. However, diesel engines still excel in low-end torque, providing a smoother and more effortless driving experience at slower speeds.

Ultimately, the choice between petrol and diesel performance comes down to individual preferences. Petrol cars offer a more spirited and engaging driving experience, while diesel engines provide a more relaxed and efficient approach.

Petrol vs Diesel Prices

A few years ago, this might have been an easier question to answer; however, with improved technology and new legislation, the lines are slightly blurred on which is actually the cheaper choice, but we’ll do our best to explain the situation.

Cost of the car:

First and foremost, you’ll be wondering which is cheaper to buy, which is likely the easiest part of this to clear up. Diesel cars, in the grand scheme of things, will always be more expensive to buy than their petrol counterparts, usually by anything up to £2,500.

On that basis, this expense will be relative to what car you’re looking at. In the case of a well-priced supermini, this extra cost can represent a 25 per cent increase of the car’s value over the petrol equivalent, but £2,500 on top of a £40,000 executive saloon might not feel so bad.

If you’re wondering why this extra expense exists, it’s largely down to the additional technology required to help diesel cars get through emissions tests.

Economy:

Now this is where diesels generally come into their own but, as previously mentioned, the lines are being blurred slightly here by petrol engines improving fast on both emissions and economy figures.

Generally speaking, you will be most likely to get more miles from the same amount of fuel in a diesel than a petrol car (when driven in the correct circumstances).

So, despite the cost of diesel being more expensive at the pump, this cost will pay out over time through enhanced MPG over petrol. Though, the gap is getting smaller by the year.

Insurance:

Because of the increased cost of the technology that keeps diesel efficient, repair costs are also increased where engine and exhaust components are concerned.

This leads to insurance costs, which are also generally higher than petrol cars due to this additional expense.

Servicing:

While petrol cars need servicing more regularly, their parts tend to be much cheaper, while diesel cars require, as already touched upon, more complex components, making a service more expensive. 

Replacing the DPF, for example, can be costly, while additional factors such as diesel requiring AdBlue can also up the price.

Residuals:

Another complex part of car ownership. Given the uncertainty over the future of diesel and the used car market in general, this can make estimating their value when selling a bit tricky.

However, for now, in most cases, a diesel should make for a better return than a petrol counterpart.

Diesel vs Petrol Emissions

Diesel engines were once criticised for their higher emissions, particularly of particulate matter and nitrogen oxides. However, advancements in diesel engine technology have significantly reduced these emissions.

Modern diesel cars often feature features like selective catalytic reduction (SCR) systems and particulate filters to capture harmful pollutants. While diesel emissions have improved, they still tend to be higher than those from petrol engines, especially in certain driving conditions.

Petrol engines, on the other hand, generally produce cleaner exhaust, with lower levels of particulate matter and nitrogen oxides. However, petrol cars can emit higher levels of carbon dioxide, a major contributor to climate change.

The choice between diesel and petrol emissions ultimately depends on individual priorities and local regulations.

How does this affect road tax?

For cars registered pre-April 2017, both petrol and diesel vehicles avoid VED charges if their emissions dip below 100g/km of CO2. However, after this time, only zero-emission cars are able to take advantage of this, with a standard £140 charge coming in for most cars – petrol or diesel – if priced under £40,000.

Then, in April 2018, an additional charge came in for diesels registered on or after this date which don’t meet Euro 6 regulations and conditions. This charge will depend upon which car you are looking at and the amount could range from as little as £20 to over £400 based on emissions, so it will be important to see where your vehicle of interest ranks in this case.

Petrol vs Diesel: Looking to the future

Petrol Diesel

The Decline of Diesel

In recent years, diesel vehicles have faced increasing scrutiny due to their environmental impact. The shift towards cleaner, more sustainable transportation has led to a decline in diesel popularity. Many major cities across the UK have implemented or proposed bans on diesel vehicles, particularly in low-emission zones. This trend reflects a growing emphasis on reducing air pollution and mitigating climate change.

Government Policies and Incentives

To accelerate the transition to cleaner vehicles, governments have introduced various policies and incentives. These include:

  • Clean Air Zones (CAZs): Cities like Birmingham, Nottingham, and Leeds have implemented CAZs, charging fees for vehicles that do not meet specific emissions standards.
  • Trade-in Schemes: Governments have offered incentives for people to trade in older diesel vehicles for newer, cleaner models.
  • Increased Parking Charges: Diesel vehicles often face higher parking fees in both public and residential areas.

The Rise of Electric and Hybrid Vehicles

The focus on reducing emissions has led to a surge in the popularity of electric and hybrid vehicles. These vehicles offer significant environmental benefits, including lower greenhouse gas emissions and reduced air pollution. As battery technology continues to improve and costs decrease, electric vehicles are becoming increasingly accessible to a wider range of consumers.

The Future of Fuel Choice

The debate over petrol versus diesel is likely to become less relevant in the coming years. As electric and hybrid vehicles become more prevalent, traditional fuel choices may fade into the background. The shift towards cleaner transportation is driven by a combination of government policies, consumer preferences, and technological advancements. While diesel vehicles may still have a role to play in certain sectors, the future of transportation appears to be increasingly electric.

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