Back when the BMW M5 hit the U.S. market in 1988, the New York Yankees' entire payroll was $18.9 million and sedans weren't supposed to take on Corvettes. BMW's performance flagship reoriented expectations of what a sedan could accomplish-your eyes tell you you're in a five-seat luxury car, yet your inner ear says this must be a Ferrari. Consider that the 1991 M5 packed more power (310 horses) than you find under the hood of the 2006 Nissan 350Z, and you understand how we've arrived at the latest M-monster-a new M5 competes with its own legacy as much as it does any Mercedes-Benz or Audi. The 2006 edition is worthy of the badge. Combine an insanely high-revving 500-hp V-10 and a paddle-shift, seven-speed sequential manual transmission with track-ready brakes, wheels, and suspension, and you've got yourself a four-door Porsche 911. Actually, that's not really fair, since the M5 is quicker than a base 911 but costs roughly the same amount of money as a Carrera S. That's why the M5 is a perpetual answer to the question, "If you could have only one car to do everything, what would you drive?" The M5 is spacious and practical, yet it reaches 116 mph in the quarter mile. It corners like a sports car yet still manages to provide supple ride quality. It's not cheap, but the M5 is a solid value. When the previous-generation M5 was introduced barely six years ago, it was widely considered to be the ultimate all-around sedan. The new car manages to make its predecessor's 394 hp look quaint, and it makes one think that BMW's going to have an awfully hard time topping its latest act. But if the past eighteen years of M5 evolution have taught us anything, it's that a team of mad German scientists probably right now are sketching out a 600-hp freak of a sedan, figuring out how to blow our minds all over again.