For years, the car collecting market has been a tale of two recoveries. Ferraris and other vintage European sports cars were soaring in price and demand. But American muscle cars—which saw irrational run-ups in the mid-2000s—were stalled.

Now, the muscle car market is back. The collectible car auctions in Scottsdale, Ariz., which ended Sunday, totaled $248.6 million, up from $225 million last year, according to Hagerty, a collectible car insurance company.