Dont you think speeding tickets would slow the game? I mean in GTA you have 2 choices:
-Driving like maniac
-Driving like normal person
If you get stoped in middle of the mission it could get stupid.
I would like more side jobs: Taxi missions, Bus(Like in VC that was a good way of earning 5$ per passanger), trucking missions, perhaps towtruck missions, and much better vigilante missions, rob the stores, houses, test drives like in LCS... These are some of features that would make this game great. Combine some elements from older games in series.
Oh yea, MUSIC. It would be nice to have popular music, like in VC, there were a lots of hits from the time the game took place at.
-Hm... should i write a novel? :)