On top of this the test car also came equipped with £2500 worth of limited slip diff, hiking the price to a breathtaking £72,450 and enabling B5 S drivers to execute 200-yard power slides pretty much at the twitch of a big toe.
What’s it like?
If the big question is, does the B5 S now ride and handle how a proper Alpina should, the answer is very nearly a resounding yes.
The 'very nearly' bit concerns the steering, which, at speed and under load through a quick corner, still lacks the lazer-guided precision you’d expect and want from an M5 wannabe. But in just about every other respect the B5 S is the car the B5 always should have been.
It now rides with the sort of mind-boggling refinement we have come to regard as common place on cars produced by company boss, Herr Bovensiepen, while the handling itself is way better than before, even if you are still acutely aware of the car’s 1720kg kerbweight during a direction change at speed.
Really start to use the power and you will still feel the tail end moving around slightly under load but the key difference is that movement now feels controlled, deliberate and usable even if you are brave enough to turn the traction control off.
As for the performance itself, it’s hard to think of any car with four doors that feels notably faster than the B5 S. In fact, I can’t think of a single example, not even the most loopy-soup offerings from AMG.
We haven’t verified the numbers yet but Alpina claims the car is good for 197mph and can knock off the standing kilometer in 22.1sec – half a second faster than the new £160,000 Aston Martin DBS.
From the way it surges forwards, with only a slightly soft throttle response in the first half second to separate you from the oncoming oblivion, the B5 S feels every inch as fast as they say it is. And its six-speed Switchtronic auto transmission works beautifully with the engine – even if you do end up leaving it in D once the novelty of using the finger buttons has worn off.
The only criticism we have concerns the way the supercharger seems to continue spinning occasionally, even after you’ve backed away from the accelerator. It feels almost as if the throttle has got stuck open momentarily, but it’s merely the result of so much energy and inertia taking a nano-second longer to calm down than you’d want. And in any case, once you’ve experienced it a couple of times it soon becomes part of the car’s hot-rod appeal.
Should I buy one?
It will be a rare beastie, the B5 S, but if you can afford the £69,950 Alpina GB requires for one, then why not?
You are unlikely to worry about the 294g/km the car produces if you are the sort of person who fancies owning a 197mph saloon. Nor is the surprisingly decent 23mpg combined figure likely to make much difference.
What’s important is that the B5 S provides a genuine alternative to BMW’s own M5 but with a less manic, more mature personality. And as a machine to use 365 days a year in the UK, it could even be a better bet than the real thing.