Just read about the photoshoot for these somewhere about a month ago. The car was static and a guy out of frame would throw gypsum under the wheel. The road is in the back area of the GM proving grounds. They made some roadsigns (I think they say the year of the Vette on the other side).
Thanks for the details. I pulled this image from an old British sports car book for kids I found at a flea market. I presumed it was a GM promo shot but was uncredited in the book.