Most economical diesel cars on sale

The most economical diesel cars promise stellar mpg figures and reduced harmful emissions. Here are the ten most efficient on sale now

Simon Ostler
Feb 7, 2022

If you're looking for headline fuel economy figures your eyes are likely to be drawn towards diesel cars. In virtually every case, the diesel version of a car will deliver better fuel efficiency than its petrol-powered equivalent.

While there have been several controversies surrounding diesel emissions and the harm they're causing to the environment, you may be wondering whether you should buy a diesel car at all. Well, manufacturers are adapting quickly to new engine standards to ensure that their diesel cars are as eco-friendly as possible. New diesel cars are now required to meet the same emissions standards as petrol models, and searching for a Euro 6-compliant diesel model should mean you'll be exempt from clean air zones like the London ULEZ.

Regardless of emissions (measured in g/km CO2), the diesel engine is unmatched by petrols when it comes to fuel economy (measured in mpg). Where the most efficient petrol cars might push towards 50mpg with frugal day-to-day use, a diesel car will be chasing 70mpg if you spend enough time cruising along the motorway.

There's no doubt that for all their emissions troubles, diesel cars are still the best way to save money on fuel without switching to an electric alternative. That said, there are a small number of ultra-efficient hybrid diesel cars that push the envelope when it comes to fuel economy figures, but may not represent the best choice if you're intending to cover longer distances.

Read on for a great list of economical diesel cars that will help to reduce your fuel costs. Or if you'd rather opt for an efficient alternative that doesn't produce harmful emissions, you could take a look at some of these hybrid cars, or even go all out on an electric car if you'd rather skip fossil fuels altogether.

Best diesel cars for mpg

Diesel emissions - need to know

Diesel cars have been targeted by several initiatives aimed at reducing the volume of harmful emissions produced by cars on the road. For a start, diesel company cars are likely to be more expensive to tax as a result of a surcharge, while newer diesel cars built post-2017 are generally more expensive to tax than petrol alternatives - although it's worth bearing in mind that older diesel models could well be cheaper to tax.

One of the major factors involved with driving a diesel car is the impact of the Ultra Low Emission Zone (ULEZ). Currently in force in Central London with similar schemes due to be introduced in city centres across the UK, these areas restrict the use of higher-emission vehicles, including diesel cars, by way of a daily charge. All drivers of diesel cars that do not meet the latest Euro 6 emissions standards will be obliged to pay the ULEZ charge, so if you're regularly required to drive in major cities, a diesel may not be your best option.

1. Mercedes E-Class

Our pick Mercedes E300de
Fuel economy 217.3mpg (saloon) 201.8mpg (estate) CO2 41g/km
Used deals from £34,780
Monthly finance from £485*

Sitting at the top of the list by virtue of it being one of the few diesel plug-in hybrid cars in Britain, there's no doubt the Mercedes E300de is one of the most efficient diesel cars on the market, with a stratospheric 217.3mpg quoted by Mercedes in saloon form and only 41g/km CO2 emissions.

As with any plug-in hybrid, the actual fuel consumption will depend on how the car is used. On short journeys, the diesel engine will rarely be required at all, as the car's large battery can power it for around 20 miles (up to 33 miles claimed by Mercedes) when the battery is fully charged. On longer trips, however, the diesel engine will see much more use, so expect to see fuel economy plummet. Fail to keep the battery charged, though, and it could prove less efficient than a similar diesel-only model due to the heavy batteries - 50mpg could even be a challenge.


2. Peugeot 208

Our pick Peugeot 208 1.5 BlueHDi 100 
Fuel economy 67.7mpg CO2 95g/km
Used deals from £6,800
Monthly finance from £149*

The older version of the Peugeot 208 we're looking at here has made a name for itself as one of the more economical cars you can buy, full-stop. The fact it's powered by what is an incredibly frugal diesel engine in the first place is then magnified by its relatively small size compared to some of the alternatives on this list. 

If you don't need a car that's particularly big, and saving money on fuel is your main priority, the small, light and nippy 208 is about as good as it gets - especially at this price point.

While diesel versions of the latest 208 are available, they are few and far between though should prove similarly as efficient.


3. Ford Focus

Our pick Ford Focus 1.5 EcoBlue 95
Fuel economy 64.2mpg CO2 91g/km
Used deals from £12,899
Monthly finance from £202*

As affordable family cars go, there are few more popular than the Ford Focus, and this model in diesel form also happens to be the most economical, too. The Focus is a competitor to the likes of the VW Golf and Vauxhall Astra, sitting somewhere in the middle in terms of price. But it represents a very enticing option in terms of value for money, there's a good deal of tech on-board including Ford's 'SYNC3' media system featuring Android Auto and Apple CarPlay connectivity.

The 95hp version of the 1.5-litre EcoBlue engine is by no means fast, but it makes the most of AdBlue technology to clean up its emissions, which makes it cheaper to tax along with the improved diesel fuel economy. There is a more powerful 120hp version of the 1.5-litre engine if you're keen for a bit more grunt, and it doesn't sacrifice too much in terms of economy.


4. Citroen C3 Aircross

Our pick Citroen C3 Aircross BlueHDi 100
Fuel economy 63.1mpg CO2 103g/km
Used deals from £11,393
Monthly finance from £195*

The general trend is for big and heavy diesel SUVs to be pretty poor when it comes to fuel efficiency, but the Citroen C3 Aircross is a small and lightweight hatchback in disguise. It may look big and chunky, but it's lighter, shorter and narrower than a Ford Focus, meaning the 1.5-litre BlueHDi diesel engine is able to produce some handy economy figures.

While the C3 Aircross should be considered as a cheap and cheerful entry into the crossover and SUV market - the cheapest Touch trim models are quite sparse when it comes to equipment, it does come with a host of customisation options when new, so the variety on offer on the used car market is expansive.


5. Honda Civic

Our pick Honda Civic 1.6 i-DTEC
Fuel economy 62.8mpg CO2 93g/km
Used deals from £12,895
Monthly finance from £252*

The Honda Civic comes in a variety of flavours. There's the Civic Type R, an aggressive and sporty hot hatch with a 2.0-litre petrol engine that burns through fuel quicker than you could tip it out of the tank. But, there are also more reserved versions of Honda's family hatchback with a much more restrained 1.6-litre diesel engine.

It still looks sporty from the outside with exuberant styling on the front and rear bumpers, but it's nowhere near as fast, nor as fun to drive. But if you're looking for strong fuel economy above all else, this is the best option open to you in the Civic range.


6. Renault Megane

Our pick Renault Megane dCi 110
Fuel economy 62.8mpg CO2 101g/km
Used deals from £8,499
Monthly finance from £157*

This is another family hatchback that offers strong fuel economy for those keen to save on their running costs. The Renault Megane offers great fuel economy regardless of whether you opt for a petrol or diesel model, but of course, it's the diesel that will help you to get the most from your investment at the pump.

In terms of fuel economy, the 1.5-litre dCi producing 110hp is the most sensible choice here, as it sacrifices very little in terms of performance alongside the more powerful 130hp version, while it is also much cheaper to buy on the used market than the similarly economical yet newer 115hp dCi. 


7. DS 3 Crossback

Our pick DS 3 Crossback BlueHDi 100
Fuel economy 62.7mpg CO2 97g/km
Used deals Limited stock

The DS3 Crossback is a similar proposition to the Citroen C3 Aircross in terms of size and uses the 1.5-litre diesel engine under the bonnet. But the more upmarket arm of the French brand offers a more high-quality feel closer to that of an Audi Q2 or Mini Countryman. As a result, the DS is more expensive than the Citroen, but it's also not quite as economical.

That being said there isn't much to choose between the two, and if you have the money to spend, there really is no reason to go for the cheaper C3 Aircross if you'd rather something with more distinctive styling and a greater array of tech inside. Android Auto and Apple CarPlay are on offer throughout the range via a seven-inch touchscreen media system, while rear parking sensors will help any nervous parkers feel more comfortable behind the wheel.


8. Dacia Sandero

Our pick Dacia Sandero Blue dCi 95
Fuel economy 62.7mpg CO2 98g/km
Used deals from £5,750
Monthly finance from £116*

We've finally come to the very cheapest car you buy brand new. The Dacia Sandero is best known for its affordability, but in diesel form, it's equally as affordable to run once you've got it on the driveway, too. 

The 1.5-litre Blue dCi engine on offer is a good one, found elsewhere in the Renault Clio on sale from 2013-2019. It produces a decent punch despite its relatively low power output, making it a capable car for commuting if you can handle its simplicity. Avoid the very cheapest Access models if you'd prefer to have a radio or air-conditioning.


*Representative PCP finance - Ford Fiesta:

48 monthly payments of £192
Deposit: £0
Mileage limit: 8,000 per year
Optional final payment to buy car: £2,923
Total amount payable to buy car: £11,926
Total cost of credit: £2,426
Amount borrowed: £9,500
APR: 9.9%

BuyaCar is a credit broker, not a lender. Our rates start from 6.9% APR. The rate you are offered will depend on your individual circumstances.


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