The M5 and M6 share a drivetrain and the platforms are obviously closely related, but the Gran Coupe is an M5 underneath – the two share the same wheelbase. But whereas the M5 shares its basic architecture with a 520d, the M6 Gran Coupe's lowliest sibling is the far posher 640i Gran Coupe, and that means the body and interior feel more special, more M6-like. The M6 Gran Coupe also continues the theme started by the original M6, with a lightweight carbon roof helping to lower the centre of gravity. You won't find that on an M5.
As with all M5 and M6 models, the 4.4-litre twin-turbo V8 sends the same whopping 552bhp and 502lb ft to the rear wheels via a seven-speed dual-clutch gearbox and active limited-slip differential.