This video tickled me pink. Not one or two, but three drivers hitching a ride back to pits on the car of Nelson Piquet in Mexico, 1986. How many other instances have there been of drivers being chauffeur to their fellow competitors?
Alonso and Webber in Germany, 2011 is the most recent I recall.
Fisichella received a rather stomach churning ride home with Schumacher (the Greater) in Germany, 1997.