http://rocbo.net/bezier/ (sorry in French best site about him) Explore it!
It was Paul de Casteljau who inside Citroën in the same time about same problem of curves ;)
Very nice, wish I had know about this when I tried making my model. A friend of mine wanted me to 3d print out a scaled down toy model. I used similar images to "trace" it out, but each image was not scaled to one another.
My model looks scary, but the toy car printed out really nice!