Check out my site @ www.ausjeepoffroad.com I am currently using adsense as part of my funding for my site, but only getting about $16 per day on it. Need to work out how to increase my revenue. I am getting about 350'000 views and only 500 click throughs.
Forums generally don't have a high CTR, try adding a blog to your site to increase visitors and grow your audience. $16/day is not bad, give it more time and work a bit harder
I checked out your ads and they were really random. You might be better off advertising with CJ and put jeep parts that break or cool upgrades for jeeps as the ads. Like right now there is a Pizza Hut one, A virgin airlines one and a car dealership... If I have a jeep, I am not looking for a new car usually. Go with parts.. You might have better luck.
have you tried amazon, they also have auto parts with ready widgets with search. even with 500 clicks at a 3% conversion rate you are bound to make more, and you will aso receive more clicks since it will be more targeted i believe.