Who wants to listen to complaining? Not me. I have no tolerance for whining and complaining. It’s hard to deal with things while you are in the car. There are only so many times you want to pull the car over. I’ve considered Nerf guns and squirt guns, and I may still try it. I was a little afraid it might escalate things, but maybe it’s worth a try. However, a solution I do every once in a while is just turn up the music…and I do it pretty loud. I sing along and keep on my poker face (while inside I’m seriously irritated) as I sing and dance to the music. I try and show that they’re not phasing me.
Great tip! Did you mean to type that they are not phasing you in your last sentence? Just checking.
Thanks, Trina. I finally got around to correcting this!
I did this over the summer when I was a nanny
I watched three boys ages 7, 8, and 10. When they were whining for no reason, I would often just turn up the volume a little and start singing. It relaxed me and stopped the whining. 
Another thing I did to keep them occupied was put books in the back seat. I couldn’t get the youngest boy to willingly pick up a book when we were at home, but in the car it was a different story (no pun intended, ha!) He would flip through books the entire car ride.
I realize I’m rambling, so I’ll stop!