Pictures here. Red circle identifies fuzzy neon <something> on the side of my car (mirror-like finish, eh? 
That’s only because birds don’t poop sideways). Other pic shows close-up. I haven’t disturbed it. It looks like a grape-sized neon tennis ball got squished against the side of the car, which was parked undisturbed in my driveway for two full days next to my neighbor’s fence. Plenty of time to build a spider condo, I guess.
Paintball attack?
Caterpillar?
Kid slime?
Maybe egg sac of spiny-backed orb weaver spider.
Looking at many pictures of spiders, nests, and egg sacs has left me feeling queasy.
I’m.not looking at thst.
What on earth color is your car? Is the whole thing made of chrome? I’ve never seen a car finish like that – it doesn’t seem to change the color values of what is reflected in it. Would you be willing to post a picture of your whole car? I’m fascinated.
Oh, yeah, probably a spider egg sac or something.
It’s a 2015 Mazda6. The pic with the spider eggs is in deep, deep shade. The color is called Deep Crystal Blue. This is the classiest car I’ve ever owned. It WAY outclasses me, as I am pretty much a slob. In a dim light (or even in sunlight, for that matter), you can’t tell it from a Lexus. Once a Maserati pulled up next to me on the highway and the two cars looked like twins separated at birth.