Like any predictive instrument, the SCM Price Guide is part science and part guesswork. The automotive alchemy we undertake to come up with these prices incorporates considerable research, tempered with a good dose of intuition.

Unique to our guide is a five-star short-term appreciation table, which rates the performance of a specific model compared to the market for the next 36 months, and the SCM Investment Grade, which rates a model's long term status in the hierarchy of collectible cars, using a letter grade from A to F.

The prices themselves represent a survey of our contributors, along with highly credible dealers and collectors who are trafficking in these cars on a daily basis. While there may have only been a handful of Porsche 917s, or Cord Sportsmen, or Hemi 'Cudas, or Daytona Competition cars built, we've found the right person in each field to help us establish a current value range.

We list our prices in a range because no two cars are alike-and no two buying and selling situations are the same either. A 1970 Boss 302 advertised in the Helena, MT, Independent Record is likely to bring less than the same car put on eBay Motors, or offered by RM Auctions at its Monterey sale.

Further, an enthusiast fresh to the collector car world with greenbacks bursting out of his back pocket will often pay far more for the "car of his dreams" than a seasoned collector who is buying his tenth, or hundredth.

Use this guide as a way to determine an approximate range of value, and let your own sleuthing skills bring you closer to an exact price. If someone is asking twice a price guide listing, find out why. And if they're asking only half the price guide value, be sure to find out why (rarely are huge bargains as good as they seem).

The SCM Price Guide is constantly evolving, and we invite your updates and corrections. Please send them to priceguide@sportscarmarket.com.

Thanks again for being a part of the SCM gang of enthusiasts. We look forward to seeing you at the next auction.