[Big Dave]

Trains are actually surprisingly aerodynamic. As we know the rear is more important than the front. If you look at a train from 7,000 feet up, it looks like a spear on tangent track. Bicycle Bob was right, the boundary layer builds up fast and the grab irons don't matter.

A Chevy Volt, as a true series hybrid is more akin to a diesel-electric submarine. The battery drives the motors and the engine/generator charges the battery. Diesel-electric locomotives eschew the battery. They use electric drive because mechanical drive is limited in how much HP they can transmit. the biggest mechanical transmissions are about 1200 HP. Today's locomotive are in the 4,000- 6,000 HP range. GE has monkeyed with a series hybrid locomotive but so far it has been a dud.

Railroads are incredibly labor-intensive and railroad people make a very high wage, so railroads are always on the lookout for cutting the amount of work it takes to move the stuff.

The best way to cut railroads' appetite (quarter-million barrels a day in the US alone) for diesel fuel is to convert them to straight electric. Proven technology but VERY capital intensive and then there the question of where do you get all that electricity?

Source: Eight years with CSX and two years with EMD.