I've posted this before, under a different name. Still shits me up to this day.
When we were still boyfriend / girlfriend, DH used to drive up the M1 to visit me at uni each week. One evening during the winter, he was driving along (alone) and glanced in the rear view mirror. He saw a little girl sitting in the rear seat. Shoulder length blonde hair, plaited into pigtails, wearing a gingham pinafore. She had her seatbelt on and was smiling 'gently'.
He looked away, looked back again. She was still there. Still smiling. Looked away again, and she had gone.
Now DH is EXTREMELY non-woo and is in no way capable of self-generating that level of detail. He wasn't particularly tired, hadn't been drinking (obviously) etc.
He saw the girl only once. We kind of forgot about it and carried on driving the car around. One evening a few months later, we were driving home from a lovely pub near us with one of my friends in the back. We were driving down a pitch black rural lane when we heard the most horrific bang on the rear door, right next to where my friend was sitting.
The only way I can describe it is someone smacking the door with an open palm. We stopped down the road outside another country pub and looked at the door. No marks at all; and there is no way on this earth that whatever hit it wouldn't have left a mark. We hadn't hit anything and nothing had been thrown up by the wheel. It just wasn't that kind of noise.
So we got over that...and then the car started having steering problems. We took it back to Audi and it went into the workshop. It spent a while in there and when we got it back it had had a significant amount of work done. We were fine with that; they assured us it had fixed the steering problem. What shit us up quite significantly was that they also told us was that the steering rack problems had been caused by the car being previously involved in a very serious head on accident.
Needless to say, we sold it very swiftly.