Reliability and fuel economy? What're you smoking? The WRX has one of the weakest transmissions ever to see a "performance" car. The EVO and STi have similar real world fuel economy numbers to the Mustang. And the Mustang is in no way competing with these cars for sales. Yes, on the street it will be in competition with those cars, but how does a car that comfortably seats four adults and has AWD compete with a pony car? Different targets there. That's where a tuned Focus would come in (unfortunately, Ford just doesn't understand this simple concept - let SVT go nuts with that car and keep the price under $24k).
There is no domestic competition for the Mustang, that much we know. The GTO and Corvette are priced out of the typical range of a Mustang, and are too low volume to have a sales impact anyway. The Eclipse, Celica, RX-8, and 350Z are the competitors. Yes, those first three are contenders, despite their hideous looks. The Eclipse and Celica will compete for sales with the V6 Mustang, and maybe even the GT if the import crowd continues to buy into the notion that the Celica looks fast, or that the new Eclipse concept doesn't deserve to be put out of my misery (seriously, that car is so painfully ugly that I can't even look at pictures for more than a few seconds without wanting to sear my eyeballs out with a curling iron).
This talk about the Cobra is starting to get rediculous. We know that SVT is going to produce a modified Mustang eventually. We don't know that it will be 2006. We don't know that it will be called Cobra. We don't know the price range. We can speculate, but to think that we can compare a car we know next to nothing about to a car like GTO, Corvette, Viper, etc etc while we discuss the new Mustang (something we know quite a bit about), is a bit rediculous.