Simplified vehicle physics for ambient traffic vehicles

I’m working on a city based racing game for iOS. I’m using Unity’s wheel collider to setup the physics for racing vehicles (both player controlled and AI controlled). The performance is very bad if I put in too many vehicles( > 30). I need a vehicle physics setup which is very simplistic and lightweight. I found that wheel colliders were the main cause of slowdown since they are slower than ray-casts and having 30 vehicles means 120 wheel colliders being updated every frame.

Is there a simplified way of implementing vehicle physics(maybe without using wheel colliders) for showing many vehicles at once on mobile platforms?

Can you just lerp the vehicles from point to point? Use something like:

Otherwise it would be pretty easy to build a simple car physics using a single rigid body, and push it around using forces. Would need to know more about the behavior you need to say more.