It gives a great breakdown on which ticket to use to get certain cars. Get the ticket you need first. Then backup your save file to a thumbdrive (also stash an additional copy on your computer as a safety) before using the ticket. Once you use the ticket if you don't get the car you wanted reload the save file from the thumbdrive and try again. I've done this several times to get the old Group C race cars from level 23 tickets.