Classic muscle cars with huge engines are hot sellers. "Right now the money's really into original big-block cars, which is cool," says Allen. "Camaros, Corvettes, Chevelles, Mustangs...those are considered the big blocks. They're the bigger cubic inches and have more horsepower, and they were produced less than the smaller-size motors. You know, these are the cars that don't get great gas mileage. We've seen those cars come back around and be worth a lot of money."