People read too much into this kind of stuff....so many believe that once this bill is passed (and it probably will be in some form) that cars like Camaros, Mustangs, GTO's, etc won't be made anymore. This type of law applies to an automakers entire lineup. That's why you see GM's latest auto show deals, those "mini-cars". They are trendy and flashy as all get up now, but in serious consideration for production because they can get 50 and 60 mpg....take 60 mpg and average it with 20 mpg and you get 40 mpg...easily beating the standard.
It's also the reason that automakers like GM buy/create other brands. They get to add them into their averages....like when GM started Saturn or bought Daewoo...suddenly GM had 10 "new" vehicles in their lineups that get 30-35 (or more) mpg....
Laws like this are why we Camaro, Firebird, GTO, and yes even Mustang owners will always have those little rice burning POS's to dust off between stoplights.