I follow this guy on twitter, @markricconi - he is a photographer for top gear and has an E61 M5.
Have a scroll through his timeline from last week to a few months ago and you will see his car on the back of a flatbed at least half a dozen times. Latest tweet about it was a joke saying when the recovery guy arrived to uplift he was asking him, how’s the wife and kids?, how was that holiday? Etc.
His car has a BMW warranty and he showed some of the invoices including one for a new engine that were eye watering.
I don’t know if the reliability of the car is worsened for him because he is using main dealers to maintain his car. In my experience they are incompetent liars. (Sure not all like that, but I’m not alone in thinking that)
He says it’s out of this world; when it works.