Most economical diesel cars on sale in UK 2019

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

Dominic Tobin
Aug 30, 2019

Diesel cars typically deliver better fuel economy than petrol vehicles, which is why they were seen as the greener choice for years.

But, with evidence that toxic emissions were often well-above legal limits in real-world driving, and news of manufacturers cheating emissions tests, diesel's reputation turned dirty.

Four years after the scandal emerged, things are different. New, stricter testing means that the latest vehicles must be as clean as petrol cars to be allowed on the roads, and a diesel engine generally remains more economical than an equivalent petrol version.

If you regularly travel long distances, a modern diesel car is likely to prove the most practical and efficient choice. It might not be as environmentally-friendly a choice as an electric car, but it doesn't require a lengthy recharging stop on a long trip.

Diesels can also be more economical than a petrol hybrid car, as these offer excellent fuel economy on shorter journeys, but are less effective over hundreds of motorway miles.

The most economical cars below are ranked according to miles per gallon (mpg) figures from a new, tougher fuel economy test known as WLTP. It doesn't fully replicate normal driving conditions, so it's also worth checking a vehicle's real-world fuel economy.

For the cleanest cars, choose one that's certified to Euro 6d or Euro 6d-Temp standards: these have been tested on the road to ensure that toxic emissions are within legal limits and include many cars sold in the past year.


Most economical diesel cars 2019


Economical diesel cars - need to know

Fuel economy
Recorded in miles per gallon (mpg), a car's official fuel economy figure is generated from a standard laboratory test, which every type of new car must go through. A new test, called WLTP, was introduced last year and has resulted in lower, more realistic figures, but they are still generally a bit higher than you'll see in real-world driving.

CO2 emissions
Cars are tested for the amount of carbon dioxide (CO2) produced in an aevrage kilometre of driving (g/km). Diesel cars generally produce less than an equivalent petrol model. Low CO2 figures can reduce your car tax (less so for cars first sold after April 2017) and company car tax, although diesel vehicles carry a company car tax surcharge.

Euro 6 emissions
Since September 2015, new cars have had to comply with Euro 6 emissions standards. These vehicles are exempt from inner-city pollution charges, including London's ultra low emission zone (ULEZ) and other clean air zones. The latest cars are tested to a tougher Euro 6d or Euro 6d-Temp standard, where emissions are tested in real-world conditions.

Britain's most economical new cars 2019 

1. Mercedes E-Class

Our pick Mercedes E300de 
Fuel economy 201.8mpg
CO2 41g/km
Latest Mercedes-Benz E-Class diesel deals from £11,995
Monthly finance from £207

Sitting at the top of the list by virtue of it being one of the few diesel plug-in hybrid cars in Britain, the new Mercedes E300de is by far the most efficient diesel car on sale now, with a stratospheric 201.8mpg official fuel economy figure and meagre 41g/km CO2 emissions.

As with any plug-in hybrid, the actual fuel consumpton will depend on how the car is used. On short journeys, the diesel engine will rarely switch on, as the car's large battery can power it for up to ??? miles when the battery is fully charged. On longer trips, however, the diesel engine will be used for most of the time, so the mpg figures may be little different to a standard diesel.

The car has only just been launched, so is not yet available as a used model. There are plenty of efficient second-hand Mercedes E-Class diesel cars to choose from.

Mercedes-Benz E-Class buyers' guide

2. Peugeot 208

Our pick Peugeot 208 1.5 BlueHDi 100 
Fuel economy 67.7mpg
CO2 95g/km
Latest Peugeot 208 diesel deals from £5,223
Monthly finance from £103

3. Ford Focus

Our pick Ford Focus 1.5 EcoBlue 95PS
Fuel economy 64.2mpg
CO2 91g/km
Latest Ford Focus diesel deals from £6,500
Monthly finance from £123

4. Citroen C3 Aircross

Our pick Citroen C3 Aircross BlueHDi 100
Fuel economy 63.1mpg
CO2 103g/km
Latest Citroen C3 Aircross deals from £8,499
Monthly finance from £144

5. Honda Civic

Our pick Honda Civic 1.6 i-DTEC
Fuel economy 62.8mpg
CO2 93g/km
Latest Honda Civic diesel deals from £6,295
Monthly finance from £143

6. Renault Megane

Our pick Renault Megane dCi 115
Fuel economy 62.8mpg
CO2 101g/km
Latest Renault Megane diesel deals from £5,495
Monthly finance from £123

7. DS 3 Crossback

Our pick DS 3 Crossback BlueHDi 100
Fuel economy 62.7mpg
CO2 97g/km
Latest DS 3 Crossback diesel deals from £16,312
Monthly finance from £225

8. Dacia Sandero

Our pick Dacia Sandero Blue dCi 95
Fuel economy 62.7mpg
CO2 98g/km
Latest Dacia Sandero diesel deals from £4,999
Monthly finance from £107

9. Mercedes A-Class

Our pick Mercedes A 180 d
Fuel economy 61.4mpg
CO2 108g/km
Latest Mercedes-Benz A-Class diesel deals from £9,400
Monthly finance from £160

10. Mercedes C-Class

Our pick Mercedes C 200 d
Fuel economy 61.4mpg
CO2 108g/km
Latest Mercedes-Benz C-Class diesel deals from £10,949
Monthly finance from £182


Latest best cars & vans

  1. Crossovers with big boots

  2. Best BMWs with reversing cameras

  3. Best hybrid car in the UK