In-depth reviews

BMW 4 Series review - MPG, CO2 and running costs

Diesel power still offers the best overall efficiency for the 4 Series, at least until the introduction of the all-electric i4 model

In terms of overall affordability the BMW 4 Series is a pretty well-rounded proposition. Although there is no plug-in hybrid version, the petrol versions are reasonably economical, the diesel-engined cars now benefit from mild-hybrid tech and there is also the efficient all-electric i4 model due for release in late 2021.

BMW claims the entry 420i petrol variant will achieve up to 44.1mpg on the combined cycle, with CO2 emissions from 146g/km, so company car users will be paying a 33 per cent Benefit-in-Kind tax rate for the 2021/22 financial year and 34 per cent thereafter.

Opting for the top-spec M440i xDrive still brings decent enough economy with an average of 36.7mpg, while the petrol-powered middle ground is occupied by the 430i with up to 42.2mpg and 153g/km of CO2.

Business users may be drawn to the 420d oil burner, with the well-equipped M Sport model returning an incredible 61.4mpg on the WLTP combined cycle and emissions of 121g/km, which places it in the 28 per cent BiK bracket.

As with the performance figures for the 4 Series, choosing a convertible model also brings a slight penalty to overall efficiency - for example, fuel economy for the 420i drop-top is down by 2.6mpg with CO2 emissions rising 8g/km on average, depending on your chosen trim.


The 4 Series Coupe starts from insurance group 30 for the entry-level 420i, rising to group 40 for the 369bhp M440i xDrive performance version. This compares favourably with the Mercedes C-Class Coupe range, which kicks-off in group 35 and rises to the top group 50 for the hot C63 S model.


When pitched against its closest rivals, the latest BMW 4 Series performs well in terms of residual values. Over a typical three-year/36,000-mile ownership period, our expert data suggests that the model should hold onto around 49 per cent of its original list price, which is markedly better than the Audi A5 Coupe at 43 per cent and the Mercedes C-Class Coupe at 40 per cent.

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