I need to go to visit my sister in Philadelphia... so I'll do the energy-conscious thing and ride the train.
Amtrak tickets: $76 each way == around $150.00. Mileage: 380 miles (approx). About $0.40 per mile.
If I were to take my car, the equation would be something like this: 380 miles @ 25 miles/gallon = about 15 gallons. A gallon of gas is about $1.60 these days. Total cost: $24.00. About $.06 per mile.
Of course, I could relax on the train, where I can't in the car, so there's that. But you gotta weight that against the time I'll spend on the platform waiting for the thing to show up (if it shows up; this particular train has an "on-time" percentage of 63% within half an hour of the schedule). This particular stop also has no monitors, and no live people; Amtrak provides no way to know whether the train will be there, even via its website. It's either gonna show up or it's not, and either way I'll be sitting there waiting.
Why would anybody but a total sucker take the train? It's pretty hard to be green under this set of circumstances.