Alpina's B6 Biturbo convertible teased

This is the Alpina B6 Biturbo convertible. And it is said to offer "open-top indulgence par excellence."

Set for a debut at the Frankfurt motor show, the Big Six features a tuned version of BMW's 4.4-litre twin-turbo V8, with power nestling at just over 500bhp (up from the 650i's 407bhp) while torque swells to a similarly formidable 516lb ft of torque (up from 442).

0-62mph is quoted as 4.8 seconds - two-shimmies of a second quicker than the 650i - while the obligatory electronic nanny pegs top speed back to 155mph.

Click through for some teaser pics, and stay tuned for more info from Frankfurt as we get it. Hopefully another colour other than bronzed-brown will be shown...