I've heard that the Rockstar team assigned to Grand Theft Auto sometimes prowels the Gamespot community with their little pads of paper and their ballpoint pens, looking for new ideas. Well.. I figured I'd post some here even though there's no chance in hell that they'd look here for ideas.
So, here we go; first, maybe the cars for the next GTA could become worn down as you drive them. By this I don't mean driving into buildings and people and they become worn down, I mean they just become older and need to be repaired internally which would give the player an incentive to have a "new" car in the game before they either go out on a mission or decide to rob a bank.
Secondly, maybe, along with the car idea, they could put in a fuel system so that all the gas stations you see in the next GTA will actually be worth something more than crashing your car into it and watching big copper metal sheets being catapulted into the air, then landing on the ground and miraculously being cleaned up by the fairies that live in my head :|. Again, this would give the player the incentive to be prepared before a big mission or whatever they may be planning on doing.
Anyway, those are my ideas, there are many more like them but those are mine. (i'll give you $20 if you can tell me where I ripped that line from) I'll be talkin to ya 8)