Regardless of what you read Law of Attraction or manifestation to be, I can point out the one thing you did wrong - you expected to see the green jeep/car. The hardest part of manfestation that about 99.99% of people completely fail to do is to just let go and stop expecting and simply trust. That's almost certainly why you were disappointed. The plain and simple reality is everyone actively manifests all the time. Manifestation is also not "wishful thinking" - it's creating your reality in your head over and over until you tend to mirror it in real life with actual work. No one can just hang around and day dream about a million dollars and poof you get it. Day dreaming is different (and completely pointless) from active manifestation.