First off:
"My Site sucks", Seriously? Get a better attitude than that, you need to be optimistic. If you think your site is the best thing since sliced bread, then thats how you should damn well act, people will see your confidence and join.
Secondly install a portal.
http://vbadvanced.com, it's free, and easy. You'll need to register on that site.
You say your a newbie to vBulletin, so come here with your questions, don't pay any money for what you can easily get for free, that goes for your styles, too. There are tons of styles and mods here for free, see if one of those suits your site better than a vBSkinworks or extremepixels skin.
EngineConversions Dot Org Statistics
Threads: 40, Posts: 233, Members: 283, Active Members: 5
Not very promising, no content. Get an RSS feed set up from News sites regarding your chosen subject, RSS feeds are simple and easy to set up, and you can make it look like it is you posting, or you can assign a bot, and it's all done from the vBulletin AdminCP!
You can also install various add-ons, such as Blogs, Arcades and SEO, give people who aren't interested in cars a reason to join too.
Remember, if they're a guest, you want them as a member.