I was walking down Alberta Street last night and there were four parked vehicles with dogs in them near the vicinity of some fine eateries. Each dog lost its shit when I walked by with my dog, including one who was spraying loads of spittle all over the back window (of a Subaru, of course). My dog decided to spend a couple of minutes sniffing a tree right there so I felt good that you would have extra slobber to clean up but felt bad for your Cujo and the stress it caused him.
Given the location of the vehicles and the time, I assume the owners were having dinner. I accept that people will leave the dog in the car to run a quick errand or two, but if you're going to park your ass for an extended period of time, leave fido at home, especially when they can't handle their shit.