Updating this article from July, we hear that RM Auctions did indeed sell the submersible Lotus Esprit that James Bond piloted underwater in The Spy Who Loved Me. During an auction this past weekend, at which 160 classic and modern cars were sold (for prices ranging from about £10,000 up to £4,000,000), the famous movie prop was gaveled down for £616,000. There’s a full description of the car and its history, along with many wonderful photographs, on this page.
During the same auction, a 1981 DeLorean DMC-12 (not a movie prop, but a sibling car to the iconic time machine in the Back to the Future films) with just under 25,000 miles on the odometer sold for £19,600.