The ugly duckling sold for just under $1.9 million, nearly $500,000 more than its twin.

A month later, an unrestored 1964 Shelby Cobra Daytona Coupe, owned by the Simeone Foundation Automotive Museum in Philadelphia, became the first automobile to be included in a new federal registry of historic vehicles, similar to the National Registry of Historic Places.

“Restoring cars is not an evil thing — when they need it,” Sandra Button, head of the Pebble Beach concourse, said in a recent interview. But, she added, “I hear from collectors all the time who say, ‘I restored my car 15 years ago, and I wouldn’t do it now.’”

Ed Gilbertson, former chief judge at Pebble Beach and a current member of the show’s selection committee, compares the trend toward preservation in classic automobiles with antique furniture, where excessive refinishing has long been regarded as an enemy of value.

“Collectors got too much in the habit of doing ground-up restorations,” Mr. Gilbertson said. “It almost makes me cry to think of the number of cars ruined by restorations they didn’t need. We’re finally learning that things are original only once.”

John Mozart of Los Altos Hills, Calif., a longtime collector whose competition-scarred 1966 Ferrari racing coupe was also chosen for the preservation class, said that enthusiasts became too caught up in vehicular cosmetics. “When I started, the only reason people bought old cars was to restore them.”

Indeed, that was the intended fate for the Superamerica Coupe, acquired in the spring by Dr. Rick Workman, a dentist from Windermere, Fla., for “slightly above” its $4 million market price.