The biggest upgrade for the M5 in the 2001 model year? An engine upgrade from the traditional six cylinder to a powerful V8, complete with a six-speed gearbox and 394 horsepower. In the words of one reviewer, "almost all of the good stuff is in the M5, not on it, so you can't see it." The car's top speed is electronically limited to 155 miles per hour - about 30 miles per hour slower than its true top speed. Still, at 108 mph, the BMW covered a quarter of a mile from a complete stop in 13.3 seconds at 108 miles per hour, so casual street drivers and commuters who want to pretend they're race car drivers will have more than enough power.