Making a Race Car Game in Unity3D

I've started work on a racing game to get myself to learn Blender, GIMP, and brush up on Unity3D. Here's the proposal document I wrote to myself:

Fancy looking document to help Developer Me persuade Publisher Me...

So far I've been following the Unity Car Tutorial for an "arcade-style race car set-up" and have gotten through section 1. I took it for a test drive and it definitely needs some tweaking, which is where the second section comes into it.

I'm not sure how I'm going to be able to make my own car after going through only this, so I'll have to have a look around to figure out what all different parts of the Car Game Object are meant to be.

EDIT: I found an even better tutorial for making a really basic car from scratch.