Photos: Unique cars on auction block

This 1950 General Motors Futurliner bus, one of three remaining survivors of 12 originally built, was the top sale at Barrett-Jackson's 35th annual classic car auction in Scottsdale, Ariz. Used as part of GM's "Parade of Progress" touring exhibit of the 1940s and '50s Motorama shows, it sold Saturday for more than $4.3 million (including buyer's premium).

Barrett-Jackson expanded its auction tent for 2006 to accommodate more spectators. The 120,000-square-foot main tent is the largest such structure in North America.

Another of Barrett-Jackson's star lots for 2006 was this 1954 Pontiac Bonneville Special, a concept car that also toured with GM's Motorama. Styled under the direction of the legendary Harley Earl, it sold for more than $3 million (including buyer's premium).

Across town at the Frank Lloyd Wright-designed Arizona Biltmore Resort, RM Auctions held its annual classic car sale. Star attraction there was this 1965 Aston Martin DB5, one of four built for the James Bond films "Goldfinger" and "Thunderball." Not a "hero car" but one used for promotions surrounding the films, it sported all the gadgets used in the movies, although the machine guns merely make sound effects rather than firing bullets. Unrestored and with only two owners since new, it sold Friday for more than $2 million (including buyer's premium).

Another 2006 RM lot with celebrity provenance was this 1964 Pontiac Bonneville Convertible originally owned by Hank Williams Jr. Known as "The Silver Dollar Pontiac," it was created by "Rodeo Tailor to the Stars" Nudie Cohn and is festooned with 350 authentic silver dollars from 1922 to 1934, themselves collectible, and more than 20 guns, also authentic but nonfunctioning. Humorously described by the auctioneer as "very subtle," it sold for $214,500 (including buyer's premium).

This 1941 Chrysler Thunderbolt, a very early example of what would now be called a concept car, was another interesting offering from RM in Scottsdale for 2006. Claimed to be in the best condition of the four remaining examples, it fetched more than $1.2 million (including buyer's premium).

RM Auctions usually offers some European sports-racing cars of the "golden era," which was best represented this year by this 1955 Maserati 300S. Its enviable competition record across Europe in the 1955 and 1956 seasons helped it bring $1.9 million (including buyer's premium).