BMW Alpina B4 VS BMW M4

One of the key differences between the B4 and M4 is the ride. While the M4 can crash over bumps and generally be a little hard to live with, the crew in Buchloe have gone after a much more plush ride. And in that they have succeeded because the B4 S is a mighty fine cruiser. Bumps are dismissed with a haughty disdain, even Sport + silliness doesn't completely write-off ride quality.

Very impressive too, is the steering. While still not at Lotus Elise levels of feel (few cars are), the Alpina tweaks connect the your palms to the road with more clarity than what you'll find in the 440i or M4. Where the M4 particularly adds too much weight, the 440i is a bit more circumspect in that regard.

And then we come to the engine. The B58 six is a belter, better even than the N55 that preceded it. It's still a 3.0-litre straight six but is part of BMW's modular engine family that starts with a 1.5-litre triple in the Mini and 1 Series. The Alpina-spec turbos are noisier, the Akrapovic exhaust lighter and also noisier. It doesn't have the all-out crackle and pop of an Audi or Merc (perish the thought), but when you're on it, the B4 means business. The 660Nm of torque, available over a wide rev range, delivers a steel fist wrapped in a velvet glove and bubble wrap - the speed builds rapidly but smoothly. 

The approach to the chassis tune seems to be based on the driving talents of mere mortals on normal roads, which is kind of like the 440i. It's terrific fun to drive hard but it's very forgiving and patient. The great thing about it is that you wouldn't think twice about jumping in it for the long haul, so comfortable and quiet is the cabin. The M4 will leave it for dead on a winding road, but that's perfectly fine.

One irritant is the replacement of the admittedly cheap BMW gearshift paddles with weirdly non-tactile buttons. They're not particularly easy to use and, probably worse for a sporty car, unsatisfying. It's an odd detail with which to go off the reservation. Cheeringly, the eight-speed ZF is its usual perfect self, so you don't have to worry too much about manual mode or go old school and use the shifter.

Marvellously.

Earlier, we said that the previous M4 (and some earlier M3 generations) never hit the dizzy heights the best like the E46 managed.

The reason why is bandwidth. Not WiFi bandwidth, but rather the newfound breadth of capability that the G83 model has acquired.

Yes, while even the slowest examples of previous M3s and M4s remained thrilling, with blisteringly potent acceleration accompanied by a soaring exhaust soundtrack, the post-E46 models seemed to become almost too obsessed with the pursuit of performance. Thunderous V8s and twin-turbo V6s are all good and well, especially when they provide explosive responses, but there’s more to sports cars than sheer bloody-minded speed.

More specifically, though the handling and roadholding were outstanding, the previous M4’s steering didn’t feel as connected or one with the driver, instead seeming a little remote and detached. Conversely, even with adaptive dampers on offer, the suspension (on Australian roads) lacked sufficient isolation from bumps and thumps, and so was never settled or calm. It was all too nervous and edgy, like a drug-addled athlete who’s indulged in too much partying.

Thankfully, the curse is broken with the latest iteration, even in the heaviest and slowest version like our M4 Convertible as tested, pushing out boundaries to thrilling effect once more.

With the newly-simplified and logically presented M performance modes only a push of a button away, the driver now no-longer has to concentrate on what setting they’re in, and instead just immerse themselves in the experience of accelerating, steering, cornering, braking and controlling this incredible sports convertible.

Tremendously strong in regular Road mode, the M4’s performance certainly lives up to the legend, stepping up into the supercar realm when Sport or Track are chosen, hunkering down as it thrusts towards the horizon with relentless speed and determination, accompanied by the gorgeous twin-turbo six’s revs as they soar towards the red line. The ultra-alert eight-speed auto’s operation is equally seamless, displaying uncanny intuition in its selection of the right ratio at exactly the right time.

These are all incremental improvements over what has come before. But what’s really changed is how rock-solid the BMW feels as it belts along at speed, magnetised to the motorway regardless of weather, its new AWD engineering keeping everything steady and planted. No more tetchiness to unnerve the driver.

Which makes the feel and fluency of the chassis even more remarkable, given that now all four wheels are driven. The very opposite of leaden or inert, the superbly weighted steering is instead light and alive in your palms, as you carve through corners with pin-point precision. Some might find it a bit too eager to change direction at first, but we reckon BMW has judged the balance just right. Its sheer agility is as life-affirming for driving enthusiasts as it is immersive. Bravo, BMW.

With so much grip and control, this is not to say that the driver can’t hang the M4’s tail out every-which-way, since the chassis set-up allows for progressive oversteer, even in Road mode, along with as much drifting as your courage allows where safe. As with the best sports cars, the M4 is as steerable from the seat of your pants as it is using the throttle.

Finally, there’s the M Adaptive chassis tune, that at long last broadens the M4’s repertoire from motorway grand tourer and rural-road blaster to city slicker and urban warrior, thanks to the suspension’s ability to better-absorb a much wider array of terrible road surfaces. Comfort now lives up to its name, with the ride – though still firm – no longer hard or crashy around town, ushering in a new level of civility that won’t fatigue or aggravate you or your occupants. We're so happy to report this progress.

One area where BMW might want to keep improving, though, is the abundance of road noise intrusion over certain coarse chip bitumen. While easily muffled by the sweet sounds of the twin-turbo six, banging audio system or dropping the roof, it now seems more obvious that the rest of the car has smartened up so much.

A small fly in an otherwise hugely satisfying ointment.