The B5 Edition 50 is Alpina’s birthday present to itself - and to a select band of its customers. Buoyed by its best-ever sales figures - over 1700 units worldwide in 2014 - the family firm of engineers and hand-crafters from Buchloe in Bavaria has ramped up the performance of its take on the BMW 5 Series.
A revised induction system and a higher-capacity fuel pump take the regular B5 Biturbo’s twin-turbocharged 4.4-litre V8 from 532bhp up to 591bhp - and torque, an Alpina specialty, goes up by 52lb ft, to 590lb ft.
The unit is mated, as usual, to a beefed-up, remapped version of the ZF eight-speed automatic transmission that features in countless BMWs. It’s controlled, in the Alpina tradition, by subtle buttons stitched into the back of the steering wheel; paddles are not offered, even as an option.
Beyond the engine mods, the Edition 50 gets a titanium Akrapovic exhaust which brings a slightly louder note and saves 17kg compared with the regular stainless steel unit. There are also forged alloy wheels, which shave off 15.6kg of unsprung mass.
Alpina claims 0-62mph will now take 4.2sec and that the top speed has increased to 204mph - making it the fastest vehicle the company has ever produced. Yet CO2 emissions are a still-respectable 221g/km, thanks to an EU combined economy figure of 29.7mpg.
The numbered production plaque is present and correct, mounted up in the headlining - but Edition 50s also get a dashboard insert personally signed by the company founder, Burkard Bovensiepen. You can also spec Lavallina leather seats with a chequered blue and green finish, harking back to the B7 S Turbo Coupé of the early 1980s.
As with all Alpinas, the B5 Edition 50 goes down the regular BMW production line and is supported by a BMW-backed warranty. This is, in theory, your only chance to buy a B5 for the foreseeable future, since UK importer Sytner no longer sells the conventional 532bhp model.
For starters, this B5 Edition 50 is seriously rapid. The regular B5 never really felt like it had a desperate need for more power or torque, but once you’ve felt the difference it makes in the Edition 50, you’re unlikely to want to hand it back.
Peak torque kicks in at a heady 3500rpm but in truth there’s more than enough below 2000rpm to get you moving quickly. Most of the time you’ll need lightning reflexes and a gentle right foot to keep the B5 anywhere near the speed limit.