I only race a few times per year. Usually there is substansial distance involved. I carpool when I can. I can easily carry 4 riders and equiptment. We try to stay close to the actual venue and use our bikes for local transportation.
My confession:
The biggest fuel waster was my across Ohio ride. A van with crew and official had to follow me the whole way to verify the crossing.
My brother drove down from Chicago to drive for me. We did set the record though.