Just as we revealed the first official photos of the all-new BMW X1, our email box was flooded with a plethora of spy shots of the next-generation BMW M5 sports sedan that is due for release in early 2011. But wait, how can we be certain that the prototype seen here is actually an M5 and not any other mainstream version of the 5-Series sedan, codenamed F10, that's expected to arrive in 2010?

Well, first of all, the test mule is equipped with the M-division's trademark four tail pipes. Then there's the wider fenders, the massive disc brakes, the 'extra-large' alloy wheels shod in beefy tires and finally, the lowered ride height. Need any more proof?

The current M5 that is powered by a 507HP 5.0-liter naturally aspirated V10 engine is one of the most high acclaimed sports sedans in the market providing supercar-like performance and handling along with daily driver comfort and livability, and BMW intends to keep it that way with the M5's replacement.

According to Carscoop sources, BMW's engineers will ditch the current model's 5.0-liter V10 and replace it with a tweaked version of the more powerful, yet lighter, twin-turbo V8 that was introduced on the X5M and X6M crossovers.

In those two models, the compact 4.4-liter twin-turbocharged V8 makes 555 horsepower at 6,000 rpm and 680Nm or 501-lbs/ft of peak torque available from 1,500 to 5,650 rpm. In the M5, the turbocharged V8 could flirt closer to the 600 horsepower barrier. In comparison, today's V10 churns out 507HP and 520Nm or 383-lbs/ft of torque.

We must note though that some recent reports sourced from the UK suggest that BMW may go for for a twin-turbocharged V10 engine generating around 600 ponies.

Either way, power will be sent to the rear wheels through a seven-speed twin-clutch transmission, and if we're lucky, BMW may offer a manual gearbox option as it does with the current M5 here in the U.S.

And for those that want a bit more practicality, BMW will also develop a Touring variant of the M5 that should arrive after the sedan model sometime in late 2011.