YEESSSS well how would i make a script that allows my enemy cars to crash into me/other enemies? im making a crash up derby type game and this is the key part of it so could someone give me a hand please if its not too much trouble 
What you want to do is create “colliders” which are flagged as either RigidBody or as Triggers. This will allow one GameObject to know when it is interacting with another GameObject. I’d suggest that if you study on RigidBodies and Colliders you will make a great start.
Here are some recommended tutorials: