Long-distance trucking seems like a huge and obvious market for autonomous vehicles. Trucks mostly travel along Interstate highways and drivers have mandatory rest periods. Usually that means the truck sits somewhere, sometimes with the engine on.
Most rest stops have also started installing "IdleAir service" which supplies Heat, AC, 120V electric and in some cases Cable TV, at the drivers expense of course.
Alas, the united states has a fairly poor cargo rail system, which in fairness is due to its spread out geography in many places.
"America's freight railways are one of the unsung transport successes of the past 30 years. They are universally recognised in the industry as the best in the world."
John McPhee has written some wonderful articles about modes of transport, and the people who work in them: http://www.amazon.com/Uncommon-Carriers-John-McPhee/dp/08654...
It comes down to highway transportation being massively subsidized in the US, to the detriment of rail. So rail is cheaper but much higher latency than trucking, with the potential for long and unpredictable delays.
Somewhat related, also great: Looking for a Ship.