What is it?
The entry-spec model we're testing here is likely to be the biggest seller in the BMW 4-series range. There are three very good reasons for this: it emits 124g/km of CO2, it can cover a claimed 60mpg on the combined cycle and it's the second cheapest model in the range.
Like all 4-series models, the 420d shares its same basic architecture with the F30-generation 3-series. It is slightly longer and wider than the Three, but substantially lower, which means it has the lowest centre of gravity in BMW’s model range.
The 420d is powered by the same 181bhp, 2.0-litre turbodiesel as the 320d. It makes peak power at 4000rpm and hits 280lb ft between 1750-2750rpm. BMW claims a 7.5sec 0-62mph time and a top speed of 149mph.
An eight-speed automatic gearbox and BMW’s xDrive four-wheel-drive system are available as options, but the model we're testing has the standard-fit six-speed manual gearbox powering the rear wheels.
Our test car is also in SE specification, the first of five trims. It includes leather upholstery, 17in alloy wheels, two-zone air-conditioning and USB connectivity as standard.