DH does a car share thing with a colleague - one week he drives them the next week she drives them.
We live in a terraced street with tiny forecourts so the front door and windows are only about 3' back from the street. It's a really quiet street with very little traffic.
On the mornings when DH's colleague picks him up, at 6:30am, she pulls up and sounds her horn. Twice. And it's not a pip-pip horn it's a loud horn. And she has the car radio on so loud I can hear her driving down the street and when DH opens the car door to get in the radio blares loud enough for me to recognise songs.
DH waits in the front room with the curtains open and light on so she can clearly see that he has seen her arrive.
He will absolutely not say anything to her about this and thinks I am being overly sensitive (I can be a bit easily annoyed by noise 
) but I think it's really rude to make that much noise - albeit only for a couple of minutes at most, at 6:30 in the morning! If I am still asleep it is loud enough to wake me.
DH doesn't want to wait outside cause she turns up any time between 6:20 and 6:35.
They are not close - she put a notice on their work car-share board, and financially it works out well.
Knowing that I do seethe at folk who talk loudly on trains and leave the office when my colleague eats an apple, I am prepared (would be happy!) to accept that Iabu, but I hate to think that our neighbours find this as inconsiderate and annoying as I do and are wishing DH would say something. (Only know the neighbours for polite hellos - doubt any of them would say anything).
So...give it to me straight. Wibu to wail and moan and plead with DH to ask her not to beep and turn down her radio?