The Alpina B6 (E63) is the second generation of the high performance grand tourer manufactured by German automobile manufacturer Alpina from 2005 to 2010. Based on the BMW 6 Series (E63), the car was available in coupé and convertible bodystyles. The B6 was introduced in 2005.
The B6 is based on the 650i and uses a modified version of its 4.4-litre N62 V8 engine,designated by Alpina as the H1 (shared with the B5 and B7). Changes to the engine include an Alpina specific block made by Steyr, a forged crankshaft and low compression Mahle pistons.The engine retains BMW's VANOS system and uses a centrifugal-type supercharger, made by ASA to Alpina's specifications and a stainless steel Akrapovic exhaust system with quad exhaust tips. These modifications allow the engine to generate 500 PS (368 kW; 493 hp) at 5,500 rpm and 700 N⋅m (516 lb⋅ft) of torque at 4,250 rpm. The choice of the forced induction V8 engine over the naturally aspirated V10 engine of the M6 grants the B6 better fuel economy figures.
The engine is mated to a 6-speed ZF automatic transmission which is claimed to be more efficient than the SMG transmission found on the M6. The transmission has a full automatic mode and a manual shifting mode, called Switch Tronic. The control system was first introduced by the company in 1993, and allows the driver to change gears via two buttons located on the back of the steering wheel. The car came standard with a limited slip differential on the coupé while it was available as an option on the convertible.
The B6 has Alpina's own suspension system designed to give a soft ride in normal driving conditions, thus maintaining the grand touring nature of the car. The B6 came with the Alpina Dynamic 20-inch alloy wheels (sets of 4-spokes in a 5-spoke arrangement).
The brakes used on the car were taken from the Middle-Eastern specification 760Li. The tyres are Michelin pilot sport units, measuring 255/35 ZR20 at the front and 285/30 ZR20 at the rear. Exterior changes over a regular 6 Series included a front chin spoiler with Alpina lettering, optional Alpina pinstripes on the exterior paint and a new rear diffuser.
The interior came standard with Lavalina leather upholstery, wood trim, BMW iDrive system, Alpina gauges and Alpina badging throughout. The interior was fully customisable by the Alpina interior department.
The B6's body in white was prepared at BMW's Dingolfing plant and was then sent to the Alpina factory in Buchloe for final assembly.