An interesting comment to a piece by James Kunstler

When folks discuss hybrids, they might as well consider combining the airship with the train somehow. Trains do use a lot of energy (far less than your jalopy, but still) - because they're HEAVY. Subtract some of the weight by adding something blimp-like (if this necessiates putting up guardrails on either side of the track, so be it) - and you'll have the most energy-efficient vehicle in history.