This 12-second long video hypothetically shows a prototype version of the next-generation BMW M5 sedan that's expected about a year after the introduction of the new 5-Series Sedan and Touring models in 2010. There's no way of being 100 percent sure if it's an M5 or not, but it certainly sounds the part. The new M5 will be powered by the same 555HP 4.4-liter twin-turbocharged V8 engine found in the X5M and X6M sporty crossovers.