The BMW 750i xDrive could be considered BMW’s seven-year itch, because it has been seven years since the company updated its flagship sedan. In that time, the Mercedes-Benz S-Class has reigned supreme and forced BMW to play catch up, which it has: The 750i xDrive’s zero-to-60-mph time of 4.3 seconds is a half-second faster than that of the Mercedes-Benz S550.

At 4,610 pounds, the 750i xDrive weighs 20 pounds less than the S550. BMW kept the car’s weight down by using ultra-high-tensile steel, aluminum, and …