Official Hover Car Tut - Unity 5

Hi,
I've been testing the newests unity 5 beta and vehicles sample assets, and I've got to say that they gorgeous and works really well.
But infortunately, the new physics in unity 5 gives me a bit of a headache, and trying to do adapt a simple Unity 4.6 tutorial led me to obviously weird result. I've been trying to tweak parameters without success, as always with the new version, the physics code aren't really working anymore.

Could anyone help me to figure out how to adapt that script for unity 5 ?
http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/hover-car-physics

Thanks for your help (and sorry for my approximative english)

 

I know this is an old thread... but just for the record: if you adjust "Drag" on the Rigidbody component to 1, the code works on Unity 5.x and 2017 just the same as it did on Unity 4.6.