Dubbed ‘Edition 50’, the B5 and B6 Biturbo versions are powered by a revised 4.4-litre twin-turbocharged V8 engine producing 600bhp at 6000rpm and 590lb ft of torque at 3500rpm. According to Alpina, this is the most powerful engine in the firm’s history.
The B5 Biturbo despatches the 0-62mph sprint in 4.2sec and has a top speed of 203mph in saloon guise and 200mph in Touring. The B6 Edition 50 coupé and convertible can also crack 0-62mph in 4.2sec. However, the coupé’s top speed is 205mph, while the convertible’s is 203mph.
The revised motor is mated to a ZF eight-speed automatic gearbox with three driving modes: automatic, sport and manual. Combined fuel economy for the B5 Edition 50 is 29.7mpg for the saloon and 29.4mpg for the Touring. For the B6 coupé and convertible it is 30mpg and 29.4mpg, respectively.
All Edition 50 models feature a limited-slip differential and an Akrapovic-developed titanium exhaust system with twin tailpipes that is 17kg lighter than a stainless steel set-up. Lightweight forged 20in alloy wheels unique to the Edition 50 also reduce weight by 15.6kg, while stopping power comes from four-piston, fixed Brembo calipers with 395mm discs and high-temperature resistant pads.