In-depth reviews

BMW 3 Series - MPG, CO2 and running costs

Excellent economy and decent CO2 emissions make the BMW 3 Series a good choice for business and private users

Overall Auto Express Rating

5.0 out of 5

MPG, CO2 and Running Costs Rating

4.8 out of 5

£39,580 to £59,165
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The latest 3 Series offers decent economy across the board; driven sensibly, even the sporty M340i can get very close to 35mpg on average. CO2 emissions are relatively low – good news for private buyers and company car users alike. All quoted figures here are for the saloon – Touring estate buyers should factor in a slight dip in economy and an increase in emissions on account of the extra weight.

The 320d Sport, with mild-hybrid tech, is the most economical choice, with a claimed maximum of 58.9mpg and CO2 emissions from 127g/km. Adding xDrive to the spec brings a further emissions increase to 135g/km – along with fuel economy of up to 55.4mpg. It’s worth sticking with the rear-drive option unless you plan to make regular use of the four-wheel drive system’s improved traction in inclement conditions.

When offered, the 330d with rear drive models returned a maximum 56.5mpg and emitted 132g/km of CO2, while xDrive models took a slight dip in fuel economy and emitted a little more CO2. Those that are seeking even more grunt won't be left too short-changed, however, because the M340d xDrive manages to combine a 335bhp output with an outstanding 48.7mpg on the combined cycle.

The most efficient of the petrol engines was the 318i SE with a claimed 44.1mpg and 144g/km of CO2. Almost the entire petrol engine range sits around this economy range; even the 330i returns up to 43.5mpg on average, with CO2 emissions from 148g/km.

The M340i on the other hand is the least efficient model in the range, but still achieves a claimed best of 36.2mpg on the combined cycle, with CO2 emissions from 177g/km.

The plug-in hybrid 330e is capable of travelling over short distances without using any fuel – its 10.5kWh battery will provide up to 36 miles of electric range when fully charged. It’s this ability that helps the 330e achieve its impressive 166.2-188.3mpg maximum claimed economy and CO2 emissions as low as 38g/km – though you’ll be hard pressed to match these figures in real life on longer journeys. It’s definitely the best choice for lower-mileage, shorter-distance drivers, however – keep your battery charged up and you could conceivably not use any fuel at all on shorter journeys.


Insurance groups for the 3 Series saloon and Touring models are competitive and range from 29 for the 320i in both Sport and M Sport trims, to group 42 for the M340d xDrive. As to be expected, the high-performance M3 sits in the highest insurance groups, with the hardcore M3 CS being the priciest in group 46.

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Thanks to the lure of the premium badge the BMW 3 Series has never suffered from terrible rates of depreciation, but as with the C-Class and the Audi A4 the sheer number of these premium models being sold each year has ultimately had a slight softening effect on their residual values.

The average retained value for the range after three years and 36,000 miles is around 50 per cent, with the 320i petrol models the strongest performers on 52-53 per cent.

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Which Is Best


  • Name
    318i SE 4dr Step Auto
  • Gearbox type
  • Price

Most Economical

  • Name
    330e SE Pro 4dr Auto
  • Gearbox type
  • Price


  • Name
    M340i xDrive 4dr Step Auto
  • Gearbox type
  • Price

Shane is responsible for looking after the day-to-day running of the Auto Express website and social media channels. Prior to joining Auto Express in 2021, he worked as a radio producer and presenter for outlets such as the BBC.

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