Hector would have darted out the car door to come to me. We've been there, done that when I first got him. He doesn't seem to be very territorial, but rather protective of me--so if i was asleep in the back seat and someone tried to open the car door, then he'd probably bark aggressively. But if I'm already out of the car, he doesn't care about it and just sees it as a chance to escape.
I also would have removed my dog in that situation, or made sure the attendant didn't open the door, or warned him, or some combination thereof. Even if I wasn't worried about the dog's reaction, I'd worry about scaring the poor attendant, or that the dog might get out and get in a dangerous situation (running into the car wash machinery, or out into the parking lot). Canine seat belts are far from foolproof and I've seen too many dogs get out of them to trust them as a form of restraint.
What did Kira do? I'm guessing it wasn't terrible or your post would be very different.
posted: My dog would not be in the situation. He would be crated in the back of the truck if I had kids in the vehicle--I would be concerned about what might happen with with a belted dog next to kids in a wreck.
I think I've read elsewhere that you have a truck with a camper shell, but I'm curious if you'd feel the same way if the dog's crate was in the passenger compartment, like in the back of an SUV. I go back and forth so much on the safest way to travel with dogs and passengers (safety for everyone involved, of course) that I like to hear everyone's views.