lol, first world problem. It's pee.
In the 3rd world, do it after a warning and the dog might get shot. There's a big difference between a free roaming dog choosing to urinate there, and the owner taking the dog over to the vehicle or stopping there to LET the dog urinate on it.
It's not going to damage your car relative to all the stuff that's already damaging your car.
Actually it will, is corrosive, but if someone walked up to my vehicle and dumped something else, equally corrosive and stinky on it, we'd have words about that too.
Move along to much more important things. There's no moral compass here. It's human nature assigning a story, a purpose, a moral compass to a nonchalant, arbitrary action of a dog, because a property, a personal space was violated.
If you have so little regard for others property, it is lack of morals that makes you not recognize the issue. Doesn't even matter if it causes quantifiable harm, is simply not acceptable in a civilized society.
My friend gets all prissy when his neighbor from a few blocks over picks up her dog's poop, bags it, and throws it in his trash bin. He said it smells...as if bagged poop really stinks any more than his trash. But that's not the issue. The issue is real that she used his bin that he's paying for, without permission.
Yes, also unacceptable, but highly possible that the feces smells worse than the rest of the garbage. My garbage hardly smells at all because I compost all organic matter, except meat scraps get frozen until trash day so they don't have a chance to sit around rotting.
Your property is not assumed to be subject to the whims of anyone else for ANY reason. It makes no difference at all if you think you can rationalize an excuse. Literally, NOW GET OFF MY LAWN!