I got a call for this one at a busy time, I was making two other cakes and had an important funeral to go to. The idea of doing it was a bit daunting, but it was for one of my best cake clients, so I had to do it.
This was my first car cake ever, and I was nervous about how to carve it. In the end I like how it turned out. I wasn't sure how much cake I needed to make, so here's a few instructions of how I did it: I used one and a half of my usual yummy chocolate cake recipe. I baked in my 9x13 rectangle, and also baked one bread pan size. (This was not necessary, you could just use the 9x13, but I was glad I had made more than just the regular recipe.)
Once cool, I cut the cake 7 inches wide and added some (using the scraps) for the roof and the back, and then carved to make the car shape.
My husband pointed out that the tires should have been bigger, (in fact, they were really small, and I made them bigger, but next time I might make them even bigger)
I did leave out a few details, because I decided if you know you can't make them look perfect, then don't put them on at all. But I think in the end it turned out great, and it was not scary at all, like I thought it might be.