Alpina B6 Biturbo Convertible

Alpina has released the first details of its B6 Biturbo Convertible, ahead of the car's public debut at the forthcoming Frankfurt motor show.

The B6 is based on the 6 Series drop-top and gets the same twin-turbocharged V8 engine as Alpina's ultra-rapid B5.

It produces 500bhp at 5500rpm, and a hefty 516lb ft between 3000rpm and 4750rpm. That’s enough power and torque to take the hefty