While it's true that trains use about half the energy per passenger-mile that planes do, and less than cars, too, most travelers have a more pressing concern: Are trains a viable alternative to flying and driving?
Fuel efficiency per passenger-mile improves with more people on the train, and highway and airport developments get far greater subsidies than Amtrak.
The logical way of measuring transport efficiency would be to compare passenger-miles
per gallon (multiplying mpg by the number of passengers).
In a typical flight, which would carry 215 passengers, it is predicted to achieve 124 passenger-miles
per gallon, almost 25 percent more than current aircraft.
The above passenger-miles
equation was estimated using seasonally-adjusted data (in inflation-adjusted dollars), in level (not log) form, with ordinary least squares containing a serial correlation correction, and no constant term.