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Diesel vs Petrol – Which Engine is Right for You?

By Nathaniel

Buying a new car can be stressful, and the decision between a diesel and petrol engine can be a tough puzzle to figure out.  Diesel engines have been picking up steam as of late, with innovations helping them run cleaner and more efficiently than before.


However, new tax legislation paired with a higher initial cost poses doubts for drivers on a budget, pushing them toward the cheaper petrol option. Keep reading our page blog Diesel vs Petrol to see which type of engine suits your specific driving needs!


Performance: diesel engine vs petrol engine


  • Performance depends heavily on what you’ll be using your car for.


  • Looking for peak power? Petrol engines spin faster, so if you want to zip around the city in a sleek, quick vehicle – petrol is likely your best bet.


  • Towing a load? Diesel engines are absolute work horses at low-rpm power, allowing them to tow larger loads with far less effort than petrol cars.



Bottom Line: Diesel and petrol engines are optimized for different types of driving – choose the one that best fits your driving needs!



Diesel vs Petrol: Economics and the 2017 VED Tax Change


  • VED Tax (Vehicle Excise Duty) Legislation was updated in April 2017


  • Previously, low-emission petrol and diesel cars were exempt from VED taxes


  • Now, the system is only free for vehicles with no tailpipe emissions, restricting the tax-break to hydrogen and electric cars



Bottom Line: Diesel cars are more expensive than before due to a change in the tax law.



Fuel Economy


  • Diesel cars are the clear winner here. Although petrol typically costs 2-3p less per litre, diesel flaunts greater mileage – meaning you’ll travel farther on the same tank of fuel in a diesel car.


  • However, the question still remains, is diesel’s fuel efficiency enough to make up for higher initial costs?


  • According to a Which? survey of 249 British vehicles, diesel engines’ superior mileage should save you around £105-£125 annually against comparable petrol engines. Of course, this would go up if you hit the road more than the average UK driver.


  • In the past, diesel cars payed for themselves in 3-4 years due to their fuel efficiency. However, the 2017 VED tax increases that time frame to 7-11 years.



Bottom Line: Diesel’s fuel economy won’t save you! Because of the updated tax laws, you’d have to drive a diesel car for 7-11 years before it becomes an economically sound purchase in the UK.


diesel engine


petrol or diesel: Mechanical Concerns – DPFs


  • Diesel particulate filters (DPFs) have been mandatory for all diesel engines since the 2009 Euro 5 Exhaust Emissions legislation.


  • The filters help diesel engines run cleaner by collecting and disposing of exhaust soot, a nasty byproduct of diesel combustion.


  • Although they help the environment, DPFs can prove expensive, as a broken or clogged filter can cost thousands of pounds to replace.


  • Diesel cars taking short trips and low speeds are the most at-risk for DPF clogs



Bottom Line: If you are a short-trip city driver, diesel cars may not be for you due to the high risk of costly DPF repairs



Environmental & Health Impacts


  • When looking at vehicle emissions, two pollutants are often taken into consideration – CO₂ (a greenhouse gas that contributes to global warming) and NOₓ (toxic nitrogen oxide gases which are detrimental to human health)


  • Recent studies find that diesel engines produce less CO2 per kilometer than petrol engines due to their better mileage, around 120 g CO₂/km for diesel against 200 g CO₂/km for petrol. (source)


  • However, diesel engines emit 30% more NOₓ than petrol engines – diminishing air quality and affecting public health.



Bottom Line: Both have detrimental impacts on human health and the environmental, taking the form of CO2 and NOx emissions. If you’re looking for a clean vehicle, stick to hybrid or electric engines.





So what’s the verdict, petrol or diesel engine? who is our winner on our diesel engine vs petrol engine battle?


Modern diesel engines have taken massive strides to become more fuel efficient and environmentally friendly. However, the new VED tax legislation makes them a less-desirable financial option than before.


If you’re willing to invest more up-front and drive frequently enough to make it cost-effective, diesel is certainly a worthwhile investment. However, for the infrequent driver who doesn’t plan on doing any longer trips or heavy towing, petrol cars represent the easier and cheaper short-term option for getting around town.



Good luck with your next purchase!

The Engie Team

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