Thank you all so much for your replies. They have greatly increased my insight into working with Projects and Tasks.
abhay, definitely some great notes there. I will refer to them frequently.
Frank, I dig your method, but I still have to think it through. I can still see value in putting tasks and projects together.
bishblaize, that's an interesting way to use OneNote. I gave up on OneNote after a couple months of use, as the volume of stuff I had to put in there made it difficult to find anything. It might be interesting to use it just for the lists, though.
Gardener, those are some good Next Actions for my car scenario. I would feel much more focused and less overwhelmed with one of those as the Next Action.
Unfortunately, I've been low on sleep these last few days so I haven't put enough quality thought into revamping my system yet. Hopefully over the weekend I can work on it. I guess I need a project called "Tweak GTD system"