That's a good idea. Here's another one: cars in the garage should have check boxes, so we can select multiple cars for oil changes, car wash, to sell or whatever. Same goes for the dealerships; should be able to buy multiple at one go.
We should also be able to change cars while out at the track in practice mode. Why do we have to spend five minutes going back to the garage, and back to the track again?
We should be able to define more parameters in online lobbies for car regulations. They started with this concept but didn't take it far enough.
We should be able to kick hosts who are absent from the game by vote. They included the "reject vote" but it never works.
Lots of little gameplay issues in GT5 that just make it cumbersome. Easy to fix.