For years, the BMW M3 has been the quintessential and benchmark high-performance mid-size luxury sedan. Competing brands have managed to come close, but the M3's overall complete package has yet to be surpassed. But now there's the ATS, perhaps one of the best new Cadillacs in years. And if the base version isn't enough, Cadillac will soon have the answer for performance seekers: the ATS-V. Set to arrive in 2016, power will come from a twin-turbo 3.6-liter V6 that'll produce around 425 horsepower.

It may just be the M3's ultimate challenger. But how does it sound? Does it look the part of a high-performance sedan? Check out this latest spy video of a prototype doing laps at the Nurburgring.