A few posts back I promised to see if people were substituting other fuels for petroleum to power the various modes transportation. The answer is definitely no.
Way back when, coal was a major transportation fuel, but this data series shows just the tail end of that era. Since the 1950s, petroleum has never provide less than 95% of the energy used by the sector.
This graph shows the importance of fossil fuels even better. In 2007, petroleum, natural gas, and coal provided 39%, 23% and 22% of all energy respectively. The much ballyhooed but always "just around corner" technologies of solar and wind continue to provide only infinitesimal amounts of power.