2021 BMW 420d M Sport Coupe Review

Great to drive still, the new 4 Series is bolstered by an interior lift – even if you don’t agree with the styling.

The lightest, most aerodynamic and fuel-efficient version of the all-new second-generation BMW 4 Series has launched.

And if your opinion reflects what seems to be the pretty widely shocked, confused and occasionally disgusted majority consensus, your next question might well be to wonder what the 4 Series’ wider package can possibly do to make up for the deficiencies of what we might call its ‘impactful’ styling. That’s a word chosen quite deliberately, by the way – because the only rationale this tester can think of to explain why this car looks the way it does is so that you might be able to inadvertently involve it in a light frontal collision and, from a distance at least, not immediately see the difference.

There are four engines on offer in this car to begin with; five versions in all if you count two- and four-wheel-drive derivatives separately. The range-topping 275kW M440i xDrive is for now the only multi-cylinder option and is one of only two all-wheel drive options, the other being an xDrive version of the 420d.

Among the more affordable four-cylinder options, though, BMW offers 135kW 420i and 190kW 430i turbocharged petrols, but only the diesels and the six-pot petrol get the benefit of BMW’s new 48V mild-hybrid assistance set-up. I’m not sure why that’s the case, but it certainly stands to widen still further the gap that has traditionally separated the real-world fuel efficiency of BMW diesels and petrols.

Our recent first drive in mainland Europe suggested that you won’t find many deficiencies about the way this car operates in top-of-the-line M440i xDrive trim. Albeit for a few different reasons, the same holds true for the less athletic 420i and 420d.

On the inside, the car is as classy, smart and pleasing to behold as its frontal styling isn’t. Getting the sculptural, lavish-looking fascia used not so long ago to drive up perceived quality levels in the 3 Series, the car mixes technological grandeur with sensory allure so much more effectively than the original 4 Series ever did. I’m still not sure BMW’s digital instruments are as easy to read as they ought to be, but it could be argued that the car’s excellent head-up display more than makes up for that. The driving position is low and snug, in a seat that supports longer-legged drivers brilliantly. The control ergonomics are utterly flawless.

In the back, adult passengers will find somewhat limited room, head room in particular being at a premium. Needless to say, if you’re buying a two-door, you probably won’t make too much use of what’s back here in any case.

When you see BMW coupes of this size out in the wild, they tend to be driven one- or two-up. If my experience is any reliable guide, they’re also often driven daily, and quite routinely a pretty long way – with owners drawn to them for their enveloping habitability and the way they mix driver appeal with first-rate high-speed touring manners so well.

BMW’s 48V hybrid set-up adds up to 8kW and an undisclosed amount of electric-motor torque into the 420d’s crankshaft. The car’s homologated peak power and torque claims remain as they were in old 12V ‘micro-hybridised’ F32-generation 420d; but BMW claims the same 7.1sec 0-100km/h sprint for the new version as it did for the old one – and the newbie’s quite a bit bigger and heavier. On-paper lab-certified fuel economy has improved, though, even if you compare this car’s more realistic WLTP combined test result with the old one’s NEDC equivalent – and that’s no mean achievement, considering the subjective gains to the car’s driving experience.

The 420d now has even better drivability, with a more authoritative and torquey sense of low-rev briskness and responsiveness about it than BMW’s already excellent four-cylinder diesels had previously. Much less part-throttle turbo lag is perceptible as you flex your right foot in a higher intermediate gear. The car accelerates notably more keenly and cleanly, and although it still runs out of puff a little once you’re stretched it beyond 3500rpm, it feels plenty fast enough to suit most tastes and purposes. Mechanical refinement is very good, and not just by diesel standards.

Without a doubt, then, this is a powertrain ready to devour long distance very easily indeed. And the chassis, too? Well, you wouldn’t call the 420d’s ride flawless, but it’d be more than good enough to cope very comfortably indeed with faster, smoother motorway surfaces, and it’s allied to handling dynamism that sets the car apart very clearly indeed.

It certainly felt a shade firmer-riding and busier in its close body control than an equivalent M Sport 3 Series although improvements to handling agility and lateral body control are harder to perceive. But that’s mainly, I suspect, because a 3 Series is such a fine-handling executive car in its own right; and the 4 Series is likewise. It’s balanced and engaging, with a carefully judged blend of directional stability, linearity of response, agility and cornering poise that’s unlikely to disappoint any interested driver. As with any typical modern BMW, the smoother the surface, and the quicker and better sighted the bend it’s running through, the more sweetly it seems to work.