can someone tell me is there a A.I mod since i wanna make cop chases in my ror.
I don't think there is. There is a way to have AI's I believe, but it's a little complex.
I do know of one way you can have a police chase. Just you'll probably have to be the cop.
Step one: Download & install this map:
http://www.austingratzer.com/rigs/downloads.php?do=file&id=69 Test Zone
Step two: Find this area in the map.
Step three: Spawn up your vehicle, put slow-mo on, hold down the forward key, and while still holding the button click the top of the screen where shown bellow. Then just let go, switch to your other vehicle, and...
Edit: Step three: To anyone that may see this post, on the newest RoR (As of when I'm making this edit) you need to hold the up arrow and while still holding it switch to the other vehicle and it should keep going. Switch to the other vehicle using the vehicles tab.
Step four: ...Begin the chase, do cool pit maneuvers and have tons of fun takedowns.
It needs to be that area or else the fleeing car will get off course, the edges keeps it in line.
Not all vehicles will work as the fleeing car, such as the Burnside. It spins out.
Hope you have lots'a fun.
Edit: Also, once you switch to your car you can turn off slow-mo. The slow-mo isn't nessicary, it just give you a chance to switch back before the other car get's away.