They aren't rendered, in some of them you can see specks of dust on the paintwork.

In this shot you can see water or polish marks in the chrome and the welds on the exhaust:

http://stadium.weblogsinc.com/autoblog/videos/HiRezPics/VE_SS_V_015.jpg

They have just been taken (or post-processed) to have that crisp, saturated look that so many car makers go for at the moment.
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Remind me to change my signature to something more interesting someday