Parkers overall rating: 4.6 out of 5 4.6

Miles per pound (mpp) Miles per pound (mpp)

Petrol engines 7.3 - 9.4 mpp
Diesel engines 8.9 - 12.1 mpp
Plug-in hybrid petrol engines 37.7 - 43.1 mpp
Low figures relate to the least economical version; high to the most economical. Based on WLTP combined fuel economy for versions of this car made since September 2017 only, and typical current fuel or electricity costs.
Based on "Weighted" mpg; figures depend on the proportion of miles driven in pure electric mode and may vary widely

Fuel economy

Petrol engines 34.0 - 44.1 mpg
Diesel engines 44.1 - 60.1 mpg
Plug-in hybrid petrol engines 176.6 - 201.8 mpg
  • Efficient diesel engines
  • 330e plug-in hybrid should be cost-effective
  • Petrols surprisingly frugal too

As with most cars, the claimed fuel economy figures for the 3 Series vary depending on the size of the wheels and tyres fitted. Generally, the larger the wheels, the higher the fuel consumption of the car.

Starting with the diesels, the 318d returns between 55.4mpg and 58.9mpg when fitted with a manual gearbox. With the automatic, BMW claims 52.3-55.4mpg. Step up to the 320d and the figures are 54.3-56.5mpg for the manual, and 53.3-55.4mpg for the auto. Specify xDrive all-wheel drive (auto only), and claimed fuel economy falls slightly to 49.6-52.3mpg. Finally, the 330d claims between 46.3mpg and 47.9mpg.

The petrols aren’t too far behind the diesels for claimed fuel economy. The 320i returns 41.5-43.5mpg, while the 330i offers 40.4-41.5mpg.

Emissions for the 3 Series are pleasingly low across the range. The best performer in the conventional range is the 318d, producing 109g/km of CO2 and 113g/km for automatic and manual gearboxes respectively. The 320d isn’t much worse, producing 115g/km and 110g/km for auto and manual models. Even the auto-only 320d xDrive emits just 118g/km of CO2.

At the top of the diesel range, the 330d emits 133g/km, while the 320i and 330i petrols produce 126g/km and 134g/km respectively.

BMW 330e mpg and CO2

Putting the regular diesel and petrol models to one side, the 330e plug-in hybrid – which joined the range slightly later in 2019 – has by far the best efficiency figures on paper.

Fuel economy is a claimed 138mpg, while CO2 emissions are just 39g/km. Both figures rely on you making the most of the 41-mile electric-only driving range capability, however, which means keeping the batteries charged up.

A full charge takes 3 hours 25 minutes using a BMW i Wallbox, or 5 hours 40 minutes using a regular three-pin plug.

Longer journeys will likely see the overall fuel economy plummet – as you’ll be able to make less efficient use of the electric motor.

However, BMW does allow you to set a preferred percentage of remaining battery charge while driving conventionally (in case you want to save the battery range for a specific part of your journey), while a clever automatic mode works with the sat-nav guidance to ensure it puts the batteries to best use over the course of the entire planned route.


  • BMW has a strong reliability record
  • New 3 Series should prove similarly dependable
  • Three-year warranty as standard

The 3 Series has a good reputation for reliability – the previous model was the subject of three recalls during its life, and none were for anything serious.

The newer model uses some new technology which we’ve found to be patchy in operation – such as disconnecting phone connections randomly and even when you come to a stop – but software updates through your dealer should sort this out in time.

Otherwise, mechanical components are tried and tested from a vast range of other BMW cars.

Ongoing running costs

Road tax (12 months) £140 - £475
Insurance group 25 - 42
How much is it to insure?