Its really tough to get a site going. Also alot of webmasters that run a Mustang website frown on members promoting your website, they feel like your trying to take there members. Believe me I know, I have done it and actually been banned because of it. You also cant mass email anyone because they literally can shut down your domain for it, been there done that.
You also have to be careful because Ive also run across the issue that other Mustang websites owners will report your email address to Spamcop as a spammer therefore potentially killing your domain.
Ive been doing this long enough to kind of know some of the tricks. I have about 50 domains.
OLE PONY is a moderator on my website and he posted a link to 7173Mustangs there.
Frankly that sort of advertising is the best way. Also members here need to add this website in there profile on other sites they belong to. When search engines grab the url that is the best way.
Lastly it just takes time. My sites been online for about 1 year and we have 250 members but it takes a long time.
Another thing Ive learned is car guys are not normally dedicated to any particular site, they will join the site read what they are interested in post a few time and rarely come back.
Its tough no doubt, hope my 2 cents worth helps out.