Sag Wagon
A car or truck that picks up or otherwise assists riders who have had to stop riding, either due to fatigue, injury, or mechanical failure. This is primarily a touring term, racers call the corresponding vehicle the "broom wagon."
Some people believe that the term derives from the verb "sag", others maintain that it is an acronym for "Support And Gear."

We have lazily adopted the term to include the rest stops that are provided along the way.