I'm gonna state mah opinionz ageen...since I have owned GT1/2/3/4 and played 5 for nearly a full day on tons of different circuit/cars etc...and I moved on FM/FM2/FM3 since their overall gameplay is worlds better.
I agree with all of that.
However why must you compare Forza to that instead of say the previous forza game?
So then that's like saying...comparing Forza 2 to Gran Turismo 3...and this entire thread would be pointless? Or, GT5 to GT4...because the only difference there is crappy "premium cars", more tracks, better graphics...and the same damn customization tables that are never going to change. Did you have GT4, 3, 2, and 1? Maybe go back and see what I'm babbling about there. I could still get custom tires sizes, engine/drivetrain swaps, wheels, body kits, decals, vinyls...only thing FM3 has vs. FM2 was...the interior view and the addition of WAY better graphics, tracks, and a bunch more cars.
GT3...still failed. Like I stated because and it still stands, at least you could paint all your cars and put rims on off them...but your point is still moot because PolyFHONY didn't change any sort of the customization gameplay...it has been the same since GT1...I know because I was a Gran Turismo fan...until I played Forza. Tuning, physics, and basically everything minus the fact GT5 has night racing and offroad racing...example: dirt, ice, snow...which is fine...because that is coming with FM4.
Gran Turismo needs to face facts...they were like the American car makers of the 70's-80's...we can keep producing junk and people will still buy it since it says Gran Turismo...and no one will beat us...guess what...Turn 10 (teh Japs)...blew it out of the water and its going to keep getting better.
Try walking up to your car and opening up the door in GT5 like you can in FM4...oh wait...lol