I used Rustoleum BedCoating in a rattle can on my hood about three years ago. It had some serious chips in it when I bought, so I figured pay to have it repainted now, or use the rattle can now and see how long you can wait to paint it later. Still looks great and is not "chunky" at all. I'd do my roof with that, but that's a lot more area. Not sure I want to take on the work! I have a Gobi Stealth on top, so I am not overly concerned about whether the paint is perfectly even like I was on my hood.
I started with tan just to try it out, but it was difficult to make consistent. I have the black now and it is perfect. You cannot tell where the deep big chips were (I did sand and primer that area). I just sanded the rest of the area a bit.