Yeah ok ; i shut up !
It's an indie game, and great start !
It's not 200 people making the game like Electronic Arts (sometimes i forget that big point

).
For some GTA style game, i don't know , i can only recomend you to search on google how it is programmed.
Caus there are games like that on DS and PSP that are very low power compared to A7 on a good PC with a good graphic card; i think it can really been done, using LOD also.