Got rusty rain rails?
Pull off those rear wings and check out the rain rails that run all the way down the trunk. Chances are they’re rusty. My car has very little rust, but these spots were starting to rust through. I broke out all the rust and scrubbed it with a good wirebrush. Then I took some of that rust remover (Naval Jelly or the like) and got it down to bare metal.
Then I got some liquid nails. Mixed up a batch and filled everything in, got it nice and smooth, then spray painted it a shiny black. Looks great and totally seals out water. Simple project and a total no brainer.