• No surprise to see diesel topping this list
• BMW 420d is the best performer, M4 the worst
• Even powerful petrol models boast decent MPG

BMW 4 Series running costs aren’t going to be miserly, but if you need to watch your wallet the 420d is probably the car for you, if you’re doing enough miles to warrant the extra costs associated with choosing diesel over petrol.

The 440i will return 31-33.6mpg according to BMW, but if you want a lower-cost petrol 4 Series we’d recommend the 430i – it claims 34.9-37.2mpg, which in some cases betters the entry-level 420i in certain specs.

The 420i with a manual gearbox claims to achieve between 35.8-37.7mpg, while the automatic remains close with figures of 35.3-37.2mpg. You can only have the automatic gearbox on all-wheel drive xDrive models and this sees a slight drop to 33.6-36.2mpg. 

Diesel numbers are more impressive – the aforementioned 420d in particular boasts 47.9-50.4mpg with the manual gearbox. As expected, we didn’t manage to consistently recreate that sort of fuel economy, but the trip computer did display figures close to these claims on a motorway run. Opt for the automatic gearbox and this dips to 46.3-49.7mpg. Go for the automatic-only xDrive and this slips down to 43.5-45.6mpg.

The more powerful 430d claims between 40.9-42.2mpg, while the xDrive drops down to 38.7-39.2mpg. The most powerful 435d reckons 39.2-40.4mpg.

Swapping into ECO Pro drive mode makes it easier to drive a little more efficiently, with the instrument cluster advising you when you are driving, or how to drive more, economically. We particularly like the way it tells you just how many extra miles you’ve added to your fuel tank’s range by driving so gently, giving a clearly visible added incentive for driving so.

M4 Coupe running costs

Bringing up the rear in terms of economy is the M4, offering 28.5mpg* whether you pick the Competition pack or not.

It’s worth noting here that servicing and maintaining an M4 isn’t for the cost-conscious – it’s an incredibly hard-edged performance car and as such it’ll hammer its way through consumables like tyres.

Green Credentials

We’ve quoted figures adjusted to the most recent WLTP fuel economy and emissions standards.

If keeping CO2 emissions low is your priority then it’s no surprise you should skip past the most polluting M4 Competition with 232g/km and concentrate on the diesel 420d. It should be of no surprise at all to hear that this is the best choice, with its 124g/km output of CO2 with the automatic gearbox. That said, the manual gearbox only emits 1g more than this. Opt for xDrive and this climbs up to 136g/km. The 430d emits 144g/km, with the xDrive rising up to 154g/km and the most powerful 435d rated at 162g/km.

The lowest-polluting petrol is the 420i and its automatic gearbox at 139g/km. The manual sees this leap up to 151g/km, matching the xDrive version and its automatic gearbox. Opt for the 430i and this is rated at 140g/km, and the 440i jumps up to 170g/km.

Reliability

• BMW 4 Series Coupe shares much with the 3 Series Saloon
• Engines and gearboxes used in a wide variety of models
• Durable, well-constructed interior is resistant to wear

We’ve got a decent selection of owners’ reviews of the 4 Series Coupe and the vast majority are four or five stars, indicating this is a BMW you can depend upon. In fact, the only two-star review comes from a buyer who doesn’t like the manual gear change, and that’s fixed simply by picking an automatic transmission, like the overwhelming majority of UK drivers.

There has been one recall for the 4 Series in 2018, relating to the EGR cooler which should be replaced. Make sure to check this has been done before buying a used model.

Don’t forget that under the skin, the 4 Series is based on the venerable 3 Series – a model that’s been around a long time.

The good news is it therefore shares components, equipment and of course engines and gearboxes from the German manufacturer’s extensive catalogue. We wouldn’t anticipate any catastrophic problems.

Your 4 Series should remain in service without issue. Typically of BMW the interior manages to straddle the fine line between luxury and durability with ease, the switchgear feeling robust and the cabin plastics resistant to marking and minor damage.