BTU per Passenger Mile and Vehicle Mile

http://www.fhwa.dot.gov/environment/aqfactbk/page13.htm

http://www.bts.gov/publications/national_transportation_statistics/html/table_04_20.html

From Oak Ridge National Lab (ORNL),

Engineering Science and Technology Division, Center for Transportation Analysis

http://cta.ornl.gov/data/tedb26/Edition26_Full_Doc.pdf

page 57, table 2.13

See bar charts of BTU for several light rail systems : Light Rail BTU