The new 6-Series, both coupe and convertible, are very, very good grand touring cars. But another 200 or so horsepower, M Division suspension tuning, and some customization of the design inside and out could just make them brilliant--and according to the latest rumors, that could happen soon.

We already know the M6 is in the works; our spies have even caught them crashed around the Nurburgring on more than one occasion.

It's been thought that the engine would be the same M-tuned 4.4-liter turbo V-8 found in the M5, but according to supposed inside info gathered by, the M6 will get a bump to 600 hp.

That's not all: while the standard M6 and M6 convertible are due in or around June 2012, the 6-Series Gran Coupe is also rumored to get its own M variant, potentially called the M6 Gran Coupe. It will share its mechanical bits with the M6, though with tuning differences for its slightly larger structure. The M6 Gran Coupe is said to arrive as early as March 2012.

If that proves true, it could put a bit of a squeeze on the M5, or it may appeal to an entirely different segment of the high-performance luxury sedan market. BMW has been slicing the gaps between its model line ever thinner for years now, to no obvious ill effect, so perhaps it will be someone's Goldilocks car.

At any rate, the new M6 range is expected to use BMW's familiar seven-speed M DCT dual-clutch gearbox to route power to the wheels, enabling the potent engine to scoot the cars to 60 mph in the low-four-second range.

The rumored timing puts the new M6 range on display at the 2012 Geneva Motor Show, likely followed with an additional showing at the 2012 New York Auto Show.