I think it really depends on what you consider to be "the class." Randy Pobst did a very good comparison of the 2011 GT with the 2011 BMW M3 a few years ago. I think you would say the M3 has gone a "different way" when you look at the specs and performance of the 2015 cars. The 2015 Mustang performance is no longer competitive with the 2015 M3 and the curb weights are very different -2015 Mustang Curb weight 3814 - 2015 BMW M3 Curb weight 3590 . In 2011 the BMW M3 had a curb weight that was 1 LB more then the 2011 Mustang GT.
Read more: 2015 BMW M3 Track Drive, Road Trip Page 2