• Best fuel economy and emissions from 420d
• More powerful diesels fare nearly as well
• Avoid the M4 if running costs are a concern

You won’t exactly be shocked to find out that the lowest BMW 4 Series Convertible running costs come from the diesel model known as 420d.

It’ll return 55.4mpg on average with the manual gearbox and 60.1mpg if you order the optional automatic ‘box.

Servicing and maintenance costs may be a little on the high side, so bare this in mind when buying the car and perhaps consider a BMW service plan for some peace of mind.

The lowest BMW 4 Series Convertible emissions, somewhat unsurprisingly, come from the 420d. This diesel version emits 134g/km.

Buying an automatic will push the emissions down further to 124g/km, meaning yet more of a tax break for company car drivers, but you do have to pay extra for it in the first place.

• BMW 4 Series uses lots of shared engineering
• Solid and hard-wearing feel to the interior
• Minor problems fixed by BMW recalls

Don’t let BMW 4 Series Convertible reliability keep you awake at night. The car is based upon existing models and tech that have been tested extensively.

The 4 Series feels solid and precisely put together, plus the materials are of a high quality and are resistant to damage.

During the car’s lifespan it has been subjected to nine recalls, usually alongside a number of other BMW models. These include issues with seat belts, fuel tank pump, rear axle bolts, power steering and airbags.

This does at least show that BMW is on top of any potential problems and willing to undertake remedial work to keep your car on the road.