Depends on the game, I'm mainly using ones with Touring Car mods, so RACE07 and GTR2, and you can use 3DSimEd for that.
I used to do Touring Car liverys for a game called Sports Car GT back in 2000/2001. For liveries I mainly use Super Touring register as they have alot of details about cars from around the world, but as your say, they mainly focus on the front and 3/4 views.