If you need to do a car cake, make sure to have them send you a lot of pictures. You should also go to this website to check on the general shape of the car in question. It has tons of car diagrams and drawings.
It also shows trains, airplanes, motorcycles, and a lot of other vehicles and random items. Most of the basics are free to use, so check it out here: Blueprints website
Kara Buntin owns A Cake To Remember LLC, online cake supplies at www.acaketoremember.com and www.acaketoremember.etsy.com