BMW tuner par excellence Alpina is returning to the motor racing scene for the first time in two decades with the new B6 GT3, which the pseudo-works firm unveiled for the first time here at the Geneva Motor Show. Based on the 6 Series, the B6 GT3 features a unique radial supercharger fitted to its 4.4-liter V8 to drive 530 horsepower to the rear wheels – in proper Bavarian style – in what looks