I would really enjoy seeing a focus on more realistic patrol car movement. There is nothing that ruins the realism more for me then when I call for backup and a patrol car plows through traffic and hits every car in site. I'm sure this would be quite a task to achieve but if you could call for backup on a low priority call and see the assisting officer calmly pull up along side of the street it would add a great deal to the mod in terms of realism. Even on a higher priority call, if the patrols could slow down sooner it would take care of a lot of the devastation.
Besides that, it would also be nice to see some kind of traffic limitation to prevent stagnant streets full of cars when you go to leave a call. I'm not a fan of being forced to drive on the sidewalks because I am to impatient to sit in the traffic for minutes.