How 'bout a carport? Sorry, Allison, I don't have a clue about any sprays and such. But my thought is...do you really want to drive away the birds? Does RainX work on metal? Or just glass?

Sherry

Would it be possible to partially prune the tree where your car is parked so that the branches don't overhang the driveway?

Ingrid

I don't park my car in the driveway, but didn't want the birds messing on it so I'd go out every night after dark and rattle the high branches with a VERY long bamboo pole. After two or three nights of this the birds, thinking a predator is after them, stopped roosting in that tree. If you rattle only the low branches they will simply move up higher not wanting to fly at night.

But it's only a temporary cure because a new batch of birds will move in after a couple of weeks so you have to keep doing it every three or four nights at least. It worked, but I finally got tired of doing it and now just hose the drive way every few days with the the rational that the droppings are good fertilizer for the blue plumbagos growing along the side of it. They do seem especially healthy and bloom a lot there. LOL

I've noticed that some people put a cover over their car at night when they park it under a tree.

There are no easy solutions to some problems. Wishing you the best.

Here is a link that might be useful: Car covers ...

I don't know if it works, but I see plenty of owl statuettes around here. People say they put them out to scare off the birds. Maybe if you placed one up in the tree it might work? It would definitely be more attractive than a scarecrow.

I know one thing that DOES work, but it's ugly and annoying. I've seen those disposable pie tins strung together by poking a hole in them---sort of like a pie-tin necklace. I've seen them hung in trees & also placed around flower beds. They shine & rattle in the breeze, scaring off birds. Ugly, but very effective.
---Laura

a tarpaulin

At the hospital where I work, everything from owl statues to clanking tin wind chimes to screaming at them was tried, all ineffective. What finally worked was a recording of a bird being attacked by a bird of prey, played over the loudspeaker before dusk until after dark set in. No more roosting after that.
I am a huge fan of birds and I find that recording to be gruesome. But if I had the problem you are having, I think I would try it. Large flocks of bird leave large amounts of droppings, unsightly, unhealthy, not to mention the smell.
Good luck.

A tarp would be the easiest, greenest, most wildlife-friendly way to go, & it would protect the car from other tree debris, too.