People can change. But you can't change people. The only person you control is yourself, so figure out what you need to do to put up some boundaries so his behavior doesn't bug you so much. E.g., stop lending your stuff to someone who doesn't take care of it; if he comes in and drops his stuff in the hallway, ask him to hang it up or put it somewhere; don't ride in his car; meet him somewhere outside of your houses; etc.
One big picture thought: why are you assuming that you are right and he is the one who needs to be fixed? You are doing what is right *for you*; so why wouldn't you assume that he is doing what is right *for him*? Why is how he maintains his house/garage/yard your business? If it's your business because he is mistreating your stuff, just stop giving him your stuff to mistreat -- that's a natural consequence.
I grew up with a mother who insisted on everything in its place; she literally could not sleep at night if there was a dirty dish in the sink or my schoolwork left out on the table. My brain does not work that way. Not just that I don't care, or that I am missing an organization gene -- when my house is too ordered/pristine, my brain starts to itch and I get antsy. I am *not* a total slob or hoarder -- but I do find minimalism extremely uncomfortable and cannot relax around too much order/structure; I need imperfection, I need things out of place, not-perfectly-aligned, the detritus of life on the coffee table, etc.
This, of course, drives my mother batshit crazy -- because she, of course, is "right," and my preference for a degree of disorder is a character flaw that must be fixed. But now it's *my* house, and I have the right to maintain it and organize my stuff in a way that makes me comfortable. And anyone who is presumptuous enough to try to "help" me fix it to their standards can go fuck themselves.