How about having a couple of credit card sized cards with
www.retro-renault.com on the front, and a brief description on the back? So that if you see someone with a retro renault you can hand them one.
They could come as standard with membership and with renewals. They don't have to be expensive, they only need get the message across.
I know a couple of people I'd give them to.
What do you think?