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.