Typically, the starting point for a resto-mod builder has been a 1950's American car, gutted like a trout and stuffed with up-to-date internals. Now the genre has grown to encompass a wider range of vehicles, even as recent as the muscle cars of the 1960's and 1970's.

"Nothing is immune, except a few special cars with inherent historical value," Mr. Davis said. "Everything else is fair game."

Jay Leno helped to popularize the trend and bring attention to resto-mods when he unveiled his immaculately reinvigorated 1955 Buick Roadmaster. In addition to a bolt-by-bolt restoration, Mr. Leno, with the help of Bernard Juchli, his mechanic, had installed a 620-horsepower V-8 sold by G.M. - and delivered to buyers fully assembled and packed in a crate - for hot-rod project cars. The finished car was, understandably, a good deal faster than it had been in stock configuration, with 236 horsepower, yet it still looked very much like a showroom condition Roadmaster.