Good: so much more than just a two-door 3 Series, terrific engine, looks

Not so good: steering not as good as it should be, pricey, four-seat only

It's odd, but I was feeling a bit 'meh' when first I drove the 4 Series. I think it was the number that put me off. Call me a traditionalist, but what was wrong with the old 3 Series Coupé badge? Given that the styling of the 4 Series takes obvious cues from the four-door 3 Series, it seemed to be little more than a marketing gimmick, and a way to justify the extraction of a higher list price, to give it an even number. Speaking of styling, at first I thought it too close to that of the 3 Series. What was the point, I pondered, of spending more money to have a less practical car, which was essentially the same to drive and look at? Just call me The Grinch...

The thing with the 4 Series though is that it's something of a slow-burner, and in that sense it's both a welcome and unwelcome reminder that it's dangerous for hacks like me to draw too many conclusions from a brief 'launch-day' test drive. Some cars need a little more time and attention to reveal their true characters and selves, and this is definitely one of them.

It didn't help that on that initial launch day, I concentrated on driving the big-seller, the 420d. Now, doubtless, there are fine reasons for buying a 420d, especially its potential 60mpg fuel economy figure and its ludicrously low motor tax rate. But if you've bought or ordered a 420d, I have some bad news for you: you've picked the wrong 4 Series. After all, the point of a coupé is not only to look good but also to back those looks up with performance. Some trousers to go with the mouth. And while the diesel is no slouch in a straight line (or indeed around the corners), trust me, it's the 428i you'll be wanting.

In spite of the badge, which revives memories of creamy-smooth straight-sixes of old, it's actually a 2.0-litre four-banger under the bonnet, but a clever twin-scroll turbo boosts the grunt to a very healthy 245hp while there's a diesel-like 350Nm of torque on tap from just above idle.

Thanks to the little button that adjusts between Eco Pro, Comfort, Sport and Sport+ modes, you really can drive the 428i exactly how you want to. I'm sure that, in Eco Pro mode, you really can get the sort of mid-forties mpg figure that BMW quotes, but to be honest, I didn't bother with it. That setting deadens the throttle just a bit too much for a car like this, where snappy, instant response is what you really want. Comfort too is just a bit wrong. Yes, it's nice and soft, but to be honest, in Sport mode, even on the gorgeous 19-inch double-spoke alloys with watch-strap run-flat tyres, there was I think only two occasions in my time with the car where I thought 'hmmm, that's a bit firm.' Just as with the switch from E90 3 Series to F30, the changeover from old 3 Series Coupé to 4 Series has brought with it an almost magical discovery of ride quality. All the fun, none of the price.

So Sport mode is where the 428i is at its best. It gives you just enough leeway for that low-down torque to give you some options for how the rear of the car behaves (a little extra throttle on the exit of a roundabout gives you a beautiful four-wheel drift, without the nervousness the no-traction-control Sport+ mode engenders) and it sounds better too. BMW has become the master of adding a little extra engine soundtrack via the stereo system, and while normally I would decry such a system as mere fakery and silliness, there's no denying that the extra timbre it adds makes the engine sound good. As sweet as the crisp, sharp sound that the actually-a-six-cylinder 435i would make? No, but given the 428i's muscular performance (under six seconds from standstill to 100km/h) I think that the case for upgrading to the full-fat six-pot has been somewhat undermined. I certainly have no doubt that the 428i is the spot-on sweet spot of the 4 Series range.

Worth the extra over a four-door 328i? Well, it kind of depends on your priorities. There's no question that the 3 Series is much more practical and the 428i's four-seat-only layout (no central rear seatbelt) caused one particular bit of child-carrying aggro for me, but there are compensations. Mostly they're in the looks department. Having begun by thinking that the 4 Series looked just a little too much like the 3 Series for its own good, time with the shape has opened up its styling to my eyes. It's leaner, lower (it sits a good 10mm closer to the ground than the saloon) and lither. And if you don't buy it in the optional Imola Blue paint job then you're really missing out. My only issue is with the little c-shaped vent on the wing, which looks only half-finished, but that's mollified by the knowledge that it's actually functional - directing air out from under the wheelarch to make the car even more aerodynamically slippery.

I love that kind of technical trickery, but sadly too much technology has meant that there is a weak point in the 428i's dynamic armoury. Yes, it has proper 50:50 weight balance and the chassis is a thing of sheer delight; poised and close to perfect. But the steering, boosted by electricity not hydraulics, just isn't right. It's nicely weighted and quick from lock to lock, but what feel there is seems utterly artificial and puts a barrier between you and the driving experience. That gorgeous three-spoke M Sport steering wheel is also just a fraction too large for my taste, which doesn't help matters.

Still, the 428i has a way of showing off its talents that is utterly bewitching. Leaning into a long, fast corner, the engine growling gently in Sport mode and the soft orange lighting of the instruments giving the cabin a calm glow, I can't think of many other motoring places I'd rather be.

Footnote: As winter really starts to grip, it's imperative to have good headlights and the 428i's are the best lamps I've come across yet. Our test car was fitted with adaptive headlights, a €547 option, and their abilities are little short of staggering. Activate the High Beam Assistant at night, and instead of simply dipping the lights when another car is detected in front of you or oncoming, something very clever happens. The lights stay on full beam, but the shape and throw of the beam alters. What you end up with is a progressively moving black-spot where the other car is, while all around it, you still have full lighting performance. It's quite brilliant, astonishing to watch and, given our long, dark winters, I'd say it's a must-have option and a terrific safety contribution.