'57 Chevys are very desirable cars today. People ask: "Where can I find one?" "Do you know anyone who has one for sale?" "Your neighbor has one for sale?" "I'd buy one if I could find one." "I've wanted one for years, but I can't find one for sale." Etc. This car has so much status today, that, out of respect and awe, you would refer to it as "one," rather than "it" or "his".