My dad got the first year run of the 2005 GT and it has been a great reliable car, it has 94k on it now and the engine/transmission are still in top notch shape, my car has less mileage than his and his car still feels tighter than mine and the engine feels stronger than mine (that 300hp shure helps out too)...

The only complaint about his is that the paint on the radio started flaking off really quickly and his door panels are falling off and the stealership wants 750 ea for every door! The dash has never rattled and the car rides smoothly and firmly and this is a completely stock 94,000 mile car! I would go for the 2007 If they could fix the minor paint problems, plus they prob were able to fix some of the minor problems like the paint on the radios and door panels, also next time you go ask if you can test drive it again and while you test drive it you could take it to a mechanic to get have him look it over for you.
Hope it works out for you dude.