When I was new at my job many years ago I did a run with an old timer, we drove for hours on a two lane highway with him driving ten Kms under the speed limit the whole way. A line of traffic so long behind us…
The odd person was able to pass and would often be honking and flipping the bird (I was slumped in the passenger seat trying to hide my face). He also didn’t buckle his seat belt or even have the courtesy to buckle it behind his back so the endless dinging would stop.. He was also 100% grey rock emotionless through this entire debacle.
Pretty sure he was a serial killer. I diplomatically tried to see what was up and spoke to all above issues but my man was a brick wall.