3D Vehicle Cakes??

I know what you mean about getting freaked out when it comes to making car cakes.  1st thing I would do is google tutorals on how to make a car cake or youtube has a lot of tutorials.  You can buy the race car pan and carve it in the shape you want.  I usually may the wheels out of rct. 

My go-to is http://www.the-blueprints.com/ you can find most cars there and you can just work from the basic 'blueprint' without having to buy it.

A nice touch I learned after doing several cars (and I wish I could go back and do it for all my past car cakes!) is to make a thick card cakeboard (covered in cake board foil) exactly the shape of your car, glue an inch or so of styrofoam to the base and glue that to a propper cake board; this creates a nice gap under your car (it helps to cover the sides of the styrofoam with black fondant.

last wee tip- crumb coat with ganache, one rough coat and another once the 1st has set- this will make all your carved edges sharper :)

HTH 

Vehicles are not my favourite but one of the things that really helps create a realistic look is lifting the car up from the base so that it looks like it is supported by the wheel rather than squashing them.

You can see some of my vehicle cakes with descriptions here:

http://www.venuscakes.com/noveltycakes/

HTH

Amanda xx

Definitely use Blueprints.com .  And leave yourself A LOT of time to do this.  I like put come modeling chocolate over the top and sides of the car then cover with fondant so I can cut away the fondant for the windows, makes a big difference.  I did a short blog post with an overview and some pics here: 

http://www.cakecreationsbybarbara.blogspot.com

Look into buying Mike McCarey's Cakenology Vol 1: Car Cakes DVD.  He walks you through making a 3D car from start to finish.  He also gives the recipes and resources (like the-blueprints.com) that he uses.  It was SO helpful when I was making my DeLorean cake.  I would work on a section and then go watch a section.  It is a great resource and I will review it again the next time I have to do a car cake.
 

Correct, the fondant won't stick to the modeling chocolate, which makes for a nice clean cut when removing the windows.  Just knead and roll out the modeling chocolate pretty much as you would fondant, but a bit thinner.