I saw this and a few ideas came across.
Run a free auto-responder on how to maintain your classic car.
Other topics perhaps.. How to find parts, how to fix, how to clean, how to "keep it real" and how to make modications without making it look terrible...
Perhaps run one on how to find a "Golden egg" inside a field of lemons? A lot of old cars are just useless in the way of how often you have to replace parts, or how crappy they are post-purchase.
There are heaps of value added autoresponders that could be prospecting tools for your website. The people who read your daily great advice trust you more and more.
Important:
Include your full name, and contact details (you must be real and trustworthy)
Ensure that they are totally confident that you will not sell their details, and all you want to tell them about is classic cars..
Make sure they can go to your website and sign up as a full member any time.. have forums, an email broadcast system, etc so it's "alive".
Just a few late-night thoughts. Hope it helps.
Cheers,
Dave
"Attitude is everything" - Keith Harrell