The track in Lakeland Florida, before it was taken down, used the rubber lining that is used inside a semi trailer. It was flexible and didn't grab you car and rip it apart. It is now used in Hudson Florida at B&B hobbies and in the next few weeks when the new track is Finished in Port Charlote, FL it will also have the same walls.
This video I did is the Track in Hudson,FL (B&B Hobbies) that uses the material for walls.