Clay Modeling

Hi!
I’ve been involved in working with blender for about 5 months now, and i am currently working on an Audi R8 that is coming along quite well (or at least I think it is). just a question, I see a lot of car models in clay renders before final renders. how do i transform my wireframe model into a clay model before my final render? Thanks!

One way http://elbrujodelatribu.blogspot.co.uk/2013/06/blender-cycles-how-to-make-clay-render.html

or http://blender.stackexchange.com/questions/1404/how-to-quickly-do-a-clay-render