I need help, I am making a roller coaster and I did it by taking a cv curve and extruding a nurbs circle with the cv curve in order to get the railing. Well I duplicated the roller coaster's cv curve so the car can follow that curve... But when it goes through the corkscrews it will go on top instead of through the corkscrew. How can I fix this... Whatever I tried didn't work. Would it perhaps be the XYZ option you have for follow?