The best place to go for raw numbers is the Bureau of Transportation Statistics. This page on their site gives energy consumption per passenger mile. Trains beat out EVERYTHING else including motorcycles for energy efficiency. Here's the page for that: http://www.bts.gov/publications/nts/html/table_04_20.html
After you look that over go to the top of the page and you'll find more tables of numbers for everything transportation related.
Next I will refer you to the Amtrak plan developed by the NARP. It includes a lot of facts and figures, and explains the benefits of rail transportation in terms the layman can understand. Download the plan in PDF format at http://www.narprail.org/plan.htm
Be sure to get the full plan, not the executive summary.
The October issue of Trains magazine had a great article on the economics of long-distance vs regional trains, busting a few common myths.
Another source of facts and figures along with an analysis of same can be found in the Selden Plan at the United Rail Passenger Alliance http://www.unitedrail.org
The California State Rail Plan at http://www.dot.ca.gov/hq/rail/railplan/csrp.htm may also be helpful.
These advocacy sites may also be helpful:
American Passenger Rail Coalition, which is made up mostly of railroad equipment suppliers and ther related businesses http://www.aprc.org/index2.html
And the National Corridors Initiative at http://nationalcorridors.org Their weekly newsletter is loaded with all sorts of information.
That may be more than you wanted.
Good luck.
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Trust God, love your neighbor, and never mistake opinion for truth.
-Mr. Toy
The Del Monte Club Car