Tyres, outside shots HDRI map and backplates are from smcars.net
Rendered at 2k resolution using PT, mostly with 4000k samples. Denoise and postwork done in Photoshop.
Render times were around 15 minutes (outside) to 40-90 minutes (black studio) on single GTX780 on OS X 10.9.2, OctaneRender standalone v1.51.
Dark studio shots:




White studio shots:


Outside shots:


