Good for you. That series needs to be rebooted and revamped dramatically. You should be able to edit the terrain so that different sections of the track can have different surfaces, such as green grass, brown dirt, and orange rock. You should be able to change the banking of curves and the length of straightaways. One interesting idea would be to make a convoluted 3-D maze of track segments, so that you might run into one or more dead ends before reaching the finish line.