Actually, the use of large turntables for car photography is common. Obviously, such a turntable is not something most amateurs would invest in, but there are quite a few commercial product photographers who specialize in the photography of large equipment that do have this sort of gear. Also, they are quite common in car shows where new models are being introduced by the mfgrs, in high end dealerships, advanced grip for movie and video production, etc...:
http://www.autoloadit.com/external-360-turntable-photography/
Don't forget that even a turntable that can handle a car can be made surprisingly compact and reasonably portable using arms that extend out to place under the tires (like a hydraulic lift), not a full circle, e.g.
https://www.youtube.com/watch?v=zE3zysJvgGM . If needed, one can bolt on a sturdy, non-flexing extension of one of the arms past the tire and place the camera at the end of it.
You might also enjoy these links:
http://carturner.com/
http://www.core77.com/posts/21672/car-studio-photography-set-ups-21672
https://www.youtube.com/watch?v=Hj0CUPABgIk
or just go to Google Images and search for {turntable auto photography}.
From the shape of the OOF blurs, I'm still sticking with my guess that this shot was done on a turntable, not on the road with an extension arm attached to the car (and the car driving in a circle). Another possibility is that the car could have been driving in a circle with the photographer at the center of the circle with his camera mounted on a tripod with a panning head, but I just don't think one could ever achieve the smoothness of the background blurs, as well as the rock solid sharpness of the car using this technique, even if he was using a geared or motorized pan head.
T
