BMW 4 Series Coupe review - MPG, CO2 and Running Costs

The 420d is the most efficient 4 Series model you can buy. Under the latest WLTP test procedure it has a best economy figure of 50.4mpg. Add the 8-speed auto and this stays the same, although the auto with xDrive four wheel drive, sees claimed economy drop to 45.6mpg.

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The petrol engines are also reasonable – a 420i with the automatic transmission emits 151g/km of CO2 and returns an official 37.7mpg overall, while the 430i can manage 37.2mpg and 140g/km.

The nice thing is that these figures aren't just spec-sheet pie-in-the-sky; from our experience you can replicate them in the real world, driving like a normal human being. One caveat for business users, though – emissions figures are dependent on alloy wheel size, so choose carefully when you’re personalising your 4 Series. You’ll also find that there’s a significant weight penalty if you choose the Convertible version, and that will have a knock-on effect on your fuel consumption. 

The xDrive four-wheel drive system will also add to your fuel costs, but not by as much as you’d think – the system is relatively lightweight for its type. Those seeking to add extra efficiency to their 4 Series should go for that automatic option – gone are the days when an auto made consumption worse, and the slick ZF-sourced eight-speed automatic actually makes the 4 Series more efficient and in most cases actually drops the CO2 by a few grams per kilometre.

Insurance groups

Lower-end 4 Series models hover around the Group 30 mark for insurance, but that grouping rises steeply once you start adding more engine capacity or power, and especially if you add on M Sport spec.

A 420i Sport is in Group 30, while the same car in M Sport spec is Group 31. The 435d xDrive is up above Group 40.

Depreciation

The BMW 4 Series retains around 45 per cent of its value over a typical three-year ownership period, and that’s about the class average.