Thanks for those speedy answers. I’m home now and have moved the car away from trees. Stopped at the grocery store, bought a dozen ant baits, and have deployed them inside the car in the areas where the ants have been swarming. I did vacuum at the beginning of this, but I think I will have to do more.
I don’t need to go anywhere until Sunday, so I can give the baits plenty of time to work.
Side note: I was speeding this morning and a motorcycle cop pulled me over. When I rolled down the window to talk to him, it must have stirred up the ants, and dozens and dozens of them swarmed on the window sill of the driver’s door. I freaked out and got out of the car. (I know you’re not supposed to do this, but it was an emergency. Sort of.) The next few minutes were spent with the officer brushing the ants off of me and me swatting the ants with a cloth I keep in the pocket of the door. He told me about the time this happened to him-- only it was tiny spiders 
and his wife refused to ride in that car until he got rid of them. The upshot is that he took pity on me, saying, “You don’t need a ticket today-- you’ve got enough trouble,” for which I was very grateful! (I really was speeding, too.) He said, “I guess it’s a good thing I pulled you over because you might have noticed the ants while you were driving and had an accident. Sometimes God uses me in mysterious ways.” How 'bout that. 