Petrol vs Diesel vs Hybrid Cars: Which is better?

Petrol vs Diesel vs Hybrid Cars: Which is better?

Published: 01.10.2020

Diesel cars have been favoured by motorists, due to their superior fuel economy and reduced car tax. However, new diesel cars no longer have this benefit. Additionally, concern over emissions from diesel cars is affecting new legislations, residual values are depreciating, and petrol and hybrid cars are becoming more and more fuel efficient. So, is the preferred fuel of old, still the fuel of choice? Here, we look at whether diesels are still economical, whilst telling you all you need to know about diesel cars and the associated pollution issues. We also reveal which alternatives can give diesel a run for its money when it comes to motorway fuel economy.

Taxation hits diesel cars hardest

  • Diesel cars usually cost more to buy than the equivalent petrol car. In the past, this wouldn’t have been an issue as it was possible to make your money back, as diesel cars had lower car tax and fuel costs.
  • Changes to the car tax system means diesel owners now pay more in the 1st year, then all drivers pay a flat rate from the 2nd year onwards. So, savings now solely come from fuel economy.
  • Hybrid cars are more fuel efficient around town but become comparatively expensive to run on the motorway. However, as technology keeps evolving, many hybrids now buck this trend.
  • Diesel cars have come under fire for their toxic emissions. However, recent tests are revealing some diesel cars emit less than the average petrol car.

Diesel vs Petrol vs Hybrid Fuel Economy

Diesel cars have been known for having better fuel economy – and for good reason. In tests conducted by Which?, diesel cars trump their petrol counterparts in fuel economy on both motorway and city driving. Diesel might cost more per litre from a station, but currently a diesel car’s fuel costs will work out cheaper than a petrol car.

Hybrid cars are quickly catching up. Having unbeatable fuel economy around town has always been the hybrid’s bread and butter. But, compared with diesel, the main weakness hybrid cars have faced is its poor fuel economy for motorway driving.

As hybrid technology increasingly evolves, we expect more cars to follow suit – with improved fuel economy. If this happens, there will be little reason to choose a diesel car.

Hybrids cost more upfront

No matter what your budget is, cost is an important consideration. The price of a car varies on manufacturer, model range and fuel type being a major factor. The more advanced or economical a car’s power-train is, the more expensive it will be to buy. So, a diesel car usually costs a minimum of £1,000 more than its petrol-engine equivalent – and the added technology in hybrids means more cost again.

How durable are a hybrid’s batteries?

Car technology is developing at a dramatic pace in the motor industry – but how durable is it? This is a particular concern for hybrid car buyers, who place huge reliance on battery power. How many years or miles will each battery last? How much will it cost to replace?

Renault are one of the first manufacturers to launch a battery leasing scheme which helps alleviate those concerns as owners can automatically swap out a damaged item for a new one. Other brands cover the hybrid and battery components under a separate warranty (typically 5 to 8 years). 

As for traditional fuel types, diesels have always been regarded as the most durable. However, all modern engines should be capable of reaching at least 200,000 miles if serviced regularly.


Cars with more up to date technology will almost certainly be the most eco-friendly. The government has an ever-changing stance on what is good and what is bad for the environment, this all makes choosing a car very difficult.

Many would think that this only applies to combustion engines, but plug-in hybrids and even pure electric cars – aren’t totally in the clear. This is because the electricity used to charge their batteries is supplied from polluting power stations. 

Petrol power has long been considered the least environmental option – slammed for its high carbon dioxide emissions. Recently, diesel cars have had their Eco-credentials stripped, with local authorities implementing ways to restrict their use – particularly in urban areas. Carmakers are at a crossroads, as the latest Euro 6 diesels are virtually as clean as petrol cars in all measurable tailpipe emissions. 

Are Hybrids Really as Green as They Seem?

Due to their electric motor, hybrids burn less fuel compared to any conventional cars and emit less greenhouse gases during use. This is great, however what about the hybrid manufacturing process? In a report commissioned by an auto industry trade group, they revealed that when you factor in the waste generated during production, the gas-guzzling Hummer SUV is actually greener than the Eco-fanatics Toyota Prius. This raises an important question: Does the pollution produced in hybrid production offset the benefits of “green” driving? In a more recent study by pressure groups Transport and Environment and Greenpeace they claimed that carbon dioxide emissions from plug-in hybrids are two and a half times higher than the figures found from the manufacturer’s tests. Official figures place the average emissions at 44g of CO₂ per km, but in the new report it argues that the figures are closer to 120g on the roads. Does this mean that consumers are being misled about the impact of the cars they drive has on the environment?

There is still uncertainty on which fuel type is better. So in order to decide which car is for you, you must take into account how you will use the vehicle. If you are looking for a small city car with low mileage per year then a pure electric would be the more cost effective option for you, however if you spend most of your time on the road travelling long distances then a diesel car would be your preferred choice. For those who are looking into buying a petrol or hybrid cars, they are well suited to many average drivers providing great fuel economy in an urban setting paired with cheaper fuel cost than diesel.