Looks pretty good but one down-side I can think of right now:
There is no visual feedback when you have selected a police car.
At least I didn't notice any, so I was never sure if I've successfully selected the car or not.

I also always tried to draw a box around one of thoses cars for faster selection, but I guess this would lower the pace of the game, so just ignore it

The hotkey idea of msl_manni is great and would make it a bit easier for my left-mouse-button