Recently I have a Car blog and forum community and also have some sponsors that pays me each month and also Google ads. But id like to learn how to make more money out of it and also get more people to sign up and join our car discussion

Thanks in advance

Read through this site and get some ideas:

101 Ways to Monetize Your Blog Without Irritating Your Readers - Inside CRM (http://www.insidecrm.com/features/101-ways-monetize-blog122007/)