In this article Guarav Nawani explains the artistic process behind the making of some images that I remember as classics.
He talks about issues such as composition, textures, colors and lighting and while (or maybe because) he does not go into many technical details this is a very interesting read.
As an encore, he then takes the model of the car and repeats the process to create a Yafray render.
The article is more than a year old, but I highly recommend it. You'll find it on Guarav's website, Burans Arts.
Update: Damn, it seems like BlenderNation hit Guarav's website hard and he ran out of bandwidth within a few hours. I've re-routed the link through the Coral Network; the link is still down for now but hopefully it will be available again shortly.