collision not working at high speeds

i have 2 cars in my scene, yet, when both are moving, sometimes the collision is ignored, and i can drive straight through the other car! How do i fix this?

check out this script on the wiki

and meshColliders don't work as well on heigh speeds collisions as a boxCollider would.

so try using box colliders if you are using meshCollider

Be sure to do your physics in the FixedUpdate method as well, if you are not already.

You may want to look into using Raycasts as another form of collision detection. May not be the solution, but I'm just trying to give you some options.

http://unity3dstudent.com/2010/08/intermediate-i01-raycasting/

I believe what is happening is that you're moving so fast, that you are skipping right through the object before it has a chance of doing any detection. This is a common problem in game design, so see if you can't find someone who talks about it online through google.