Funky Multiplayer Physics Collisions

We initially setup a vehicle with a single box collider and four wheel colliders, then followed this tutorial to get multiplayer going. It worked great except for when two cars (belonging to different clients) would collide - they'd bounce into the air or get sent off in another unrealistic direction. Often it gives the effect that cars are using each other as ramps or trampolines....

Funky Multiplayer Physics Collisions