As the pair of development cars pounding the Nurburgring in this video (below) reveal, the next M5 - which is due in 2011 - will retain the trademark M-car quad exhaust pipes, although these have been moved out to the edge of the bumper.
What won't be carried over is the current M5's V10 powerplant. That will be replaced by a turbocharged V8, most likely a unit closely related to the twin-scroll, twin-turbo 4.4-litre unit from the X6 and X5 M models, so expect a power out put of around 540-550bhp (the X6 M gets 547bhp).
Unlike the big M-SUVs, the M5 will be rear-wheel drive rather than four-wheel drive, with power fed to the wheels via a six-speed manual (thank goodness) or BMW's Seven-speed DCT twin-clutch transmission.
Despite the heavy disguise, it's clear that the new 5-series will be a bigger car than its predecessor, with more flowing lines. Despite the larger dimensions, however, BMW insiders say that there will be no weight gain over the current car's 1830kg kerb weight.