Car gets very heavy and becomes slow once it touches ground

Hi

im trying to create car movment for my game and iv tested it out on a flat plane what the car accelerates fast but then what I transfer over to my game and the track i have it becomes very slow I have no idea why. Im trying to work out if iv set something in the inspector wrong for the track mesh.

This is whats on the track inspector


These are my wheel coliders


Video of my problem

 

I looks OK but are you sure the box collider is not dragging on the floor?
Your spring setting may need to be stiffer too.