I hate to see complaints that SS vs R/T is not "fair". For someone who wants a muscle car under 40K, it is a perfect comparison.
Keep in mind that there "should" have been a Camaro Z28 with a supercharger and ~550hp. It was axed by the crisis at GM.
See one article about it here:
http://www.motorauthority.com/previe...amaro-z28.html
If Dodge quits producing (heaven forbid) the SRT after it comes out of bankruptcy, does the now-top-model R/T have to be tested against the GT 500 for a fair comparison? Of course not.
To the extent that you would line up a top/middle/base grouping for Ford, GM, and Dodge it would be Shelby/GT/V6 vs. Z28/SS/LS vs SRT8/RT/SE. Take out the stillborn Z28 and the SS is the highest model available, but its price and volume targets are more appropriately compared to the R/T and GT.
I think an SRT vs SS vs "the most Shelby-tastic Mustang Ford sells" test would be great. It could crown the king of the muscle cars. But then the testers would ramble on about the huge price advantage of the SS, and it would probably win that test too.
Bottom line, magazine tests are fun, but you don't have to buy what they tell you. The Chevy is the winner by the numbers, but to me is just not as cool.