Amen to that. In my case, some of the layovers have a company car. To have to tip the van driver on top of being without transportation for the day is a double whammy.

Having said that, if I had more, I'd tip more, but for now most of my tips I give for extra duty (like if they make a stop so I can grab some food, or if they give me a ride to a recreation spot, which going back to the point would be other than routine company business).