Like Jeff said, they will find you. For starters, there are several magazine editors that frequent this site and I've been contacted many times for e-mail addresses of owners of cars on this site.
You also need to be seen at major car shows. Did you happen to see all the Primedia guys combing the grounds at the Car Craft Summer Nationals? They had Wes Allison along, too. He's Primedia's motion photography guru.
As for the car, they are always looking for the complete package, something that will not only interest subscribers, but also get people to pick it up off the rack.