If you design a car that you think will perform well, you should build it and see! Virtual Car is designed to print templates that will help you build the car. The Preview mode lets you look at the set of templates that will be printed, without actually printing them. This is a good idea, to make sure that the templates are going to look like you expect them to look. It is also a good way to keep track of the number of layers that you will need to cut out.