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
A $62,000 car is not in the same class as the Mustang.
Which is why I said it really depends on how you define " the class." If you look at the cars in the SCCA SOLO F Stock class, then there are several cars that weigh less then the Mustang - assuming the 2015 Mustang GT winds up in the same or similar class. In 2011, many were glad to "see the BMW M3 and the Mustang GT in the same "class,"" in terms of performance - if not price. Then, the Mustang was viewed as a "low cost "BMW Class" car." The 2016 Camaro sounds like it will also "take a different path" from the Mustang in terms of weight - and presumably performance.
2013 Mustang GT Premium Convertible
Candy Apple Red, Auto, FRPP Tune, GT500 Axlebacks, KONI Yellow Sport (adjustable dampers), FRPP Front and Rear swaybars, Custom Removable 4 Point Roll-Bar, BOSS 302 Low Expansion Brake Lines, Roush side splitters, GT500 spoiler, Redline Tuning hood struts,18" Ford Chromed Aluminum Wheels (9R3Z-1K007-A), Michelin Pilot Super Sports - 235X50X18
2011 Mustang V6 Premium Convertible - Gone