The new Mini is designed to look like an earlier, and even tinier, car. But it has garnered a genuine following in its own right.

Importantly for its collectible status, the Mini has more than just cute retro looks. It's actually quick and fun to drive.

"It's what the New Beetle needed to be, but isn't," said Hagerty.

The Mini also has excellent short-term resale value. In fact, the Mini is a perennial top-finisher for Kelley Blue Book's annual resale value awards. After five years, a Mini Cooper is worth about half its original price. Most cars are worth a third or less.

Resale value as a used car is a good predictor of future collectibility, said Hagerty, since its based on the same market drivers of supply and demand,