BMW 3 Series (2012-2018) review - MPG, CO2 and Running Costs

Thanks to special fuel-saving technology and the reduced weight of the current BMW 3 Series, all of the four-cylinder diesel engines now emit less than 140g/km of CO2. That makes it really cheap to tax, keeping running costs as low as possible.

We'd go for the 320d EfficientDynamics Plus model, which emits only 102g/km of CO2 and returns an excellent 72.4mpg. Spec the sleeker-looking ED Sport model and that jumps to108g/km, but the improved residuals should help keep costs down.

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The whole range is pretty good, in fact – even the turbocharged 2.0-litre 330i manages to keep CO2 emissions at a reasonable 151g/km. But if you want rock-bottom running costs and have regular access to a charge point, then try the 330e for size. It has 44g/km CO2 emissions, and BMW claims it’ll do nearly 25 miles in electric only mode.

However, when Auto Express tested a 330e, it didn't perform as well as a VW Passat GTE hybrid on a similar test route. We managed 47.2mpg using a full tank of fuel and four full charges of the battery, but as the engine cuts in more frequently than in the GTE, it puts pay to the 330e’s economy. The 330's 41-litre fuel tank is 19 litres down on a 320d’s, too, so your range will be shorter if you always rely on the engine.

Used - available now

2020 BMW

3 Series

62,840 milesAutomaticDiesel3.0L

Cash £22,754

View 3 Series

2022 BMW

3 Series

38,638 milesAutomaticDiesel3.0L

Cash £32,799

View 3 Series

2022 BMW

3 Series

52,709 milesAutomaticPetrol2.0L

Cash £20,703

View 3 Series

2022 BMW

3 Series

24,956 milesAutomaticPetrol2.0L

Cash £23,618

View 3 Series

You can't recharge the 330e battery pack on the move, but you can store energy for low-speed use later in your journey. Stick in Eco Pro mode and on-screen guides will prompt you to stay below 50mph and lift off the throttle on the approach to roundabouts and junctions.

In full electric mode we managed 17 miles before the engine cut in, yet it takes a lot more concentration than in the VW to prevent the engine cutting in. Recharging from a standard mains plug takes around three-and-a-half hours.

List prices for the 3 Series are on a par with rivals, as the range starts from around £28,000, but that’s only for the basic three-cylinder 318i in SE trim.

Insurance groups

Insurance groups for the BMW 3 Series kick-off around 18 for a basic 316d SE. The 320d SE and 320d M Sport both sit in group 28, whereas the 335d xDrive M Sport sits all the way up in group 40 – bizarrely – a faster 340i sits in group 36. An M3 is in group 45.

Depreciation

No BMW 3 Series suffers from particularly bad depreciation, but if value retention is a priority then some models fare better than others. A manual M3 is the best performer, while a 335d xDrive is pretty good, too. Most 320ds retain around 45 per cent, but the plug-in 330e models fall slightly shy at between 38 and 40 per cent. The Jaguar XE and Mercedes C-Class are – broadly speaking – very similar.