Try Scratch X first, then if they are in fact water spots, try soaking them with some vinegar using a towel. They may be etched into your paint but the above steps will quickly determine this. I refuse to park under trees any longer. Not only to you get sap and debris falling on your MINI, but here at least you get bird crap as well. I've got a sunshade so I don't need the shade of the tree to keep the sun off my interior.
Good luck.

 

Not to mention that they, and their branches, fall. A big pine tree branch fell and took out my son's car's passenger side mirror. It just missed hitting the whole side of the car.

 

claybar first, then mild polish if it doesn't work (like scratch-x).

 

Etched into the paint? If they are etched into the paint what is my next step?

What brand of claybar AND can a person find a quality claybar from a large store chain or would a auto chain be the best location?

 

I use the Meguiars Clay Kit which ran me about $18 for the bar + a QD (lubricant) (all in the same box). I picked it up at Autozone.

 

I recently dealt with very persistent water spots on 2007 Black Corvette that was just a few days old. The owner had picked it up from the manufacturer and drove it back to LA--but it got hit by hotel sprinklers in New Mexico on the way back home.

His first attempt at fixing it was taking it to a local car wash/detailer where they always have exotics like Lambos and Ferraris all the time--the guy used a rotary buffer and a clear coat wax which did absolutely nothing for the water spots, but he did instill holograms, gouges, and scratches into the paint.

Unhappy with the work, he searched the net and found me, and my task was to remove the water spots and fix the damage caused by the other guy.

I always use the mildest solutions first, also known as least aggressive. I clayed the paint to see if the water spots were just on the surface. This made the paint smooth to the touch, but didn't affect the spots.

So I buffed the paint with M80 and M83 and my rotary buffer to fix the holograms. Although Corvette paint is extremely hard, I found this to be enough to fix the previous damage. And the water spots seemed to have disappeared. I followed this with the PC and put on Epic.

A week later, the customer called me and said that although in the sunlight the spots weren't visible, he was able to still see them at night under a streetlamp. That wasn't good---we couldn't see them as I buffed them the first time.

After doing a little bit of research, I was advised that wetsanding with 3000 grit may be the next course of action. Often times a water spot can actually etch the surface causing little craters below the surface, and no amount of claying or buffing will solve the problem.

But I decided I would try compounding first using the rotary with M84 and a W7006 cutting pad--the most aggressive combo you can go with Meguiar's on the rotary and still using a foam pad.

The customer brought the car to me and parked it outside my shop in a way that he could see the water spots. So I buffed them one by one until they were no longer visible--which didn't take long--the challenge was seeing them so they could be removed.

So that's what it took to remove the water spots off this 3 day old black Corvette.

Anytime you get hit with sprinklers, don't let the paint boil in the sun, especially if you have black paint. You never know how hard the water is until you have to hire a pro to remove them.

Vinegar will work if the mineral deposits are only on the surface of the paint and haven't etched themselves into the paint. Acid rain is especially troublesome for your paint, I know of pros who have refused to work on paint damaged by it.
http://www.epa.gov/acidrain/

Good luck!

Richard