question about car models & double sided faces

[alex25]

permission was granted so expect a new track soon.

i've committed the track (bahrain) but it still needs some of work. i seem to be having problems with the vertical surfaces. in particular the pitwalls and the rails around the track behave very strangely. when the car makes contact (i've tried both the F1-02 and the M3) it kind of goes through them and then it starts jumping wildly. maybe somebody can figure out what's wrong. i'll add the bumpiness for the curbs and the appropriate friction coefficients for sand/grass/roads/etc soon.

--alex--