Subsidized commodities tend to be available in inflexibly limited amounts. And by "inflexibly limited" I mean even more inflexibly limited than mere nature requires.

The more usual case, with natural gas and petroleum-derived fuels, of heavy consumption taxes -- negative subsidy -- makes government push them by means that are available only to it. Laying urban developments out in such a way that people have to drive long distances often, for instance.

--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html

This is an interesting argument, is there actual correlating data to back it up or even historical causal evidence to prove it?

Correlating data are more likely to be available than proof, I think, if by proof one means Hansard or local council excerpts saying anything like "We must make them burn more fossil fuel"; one would not expect such candour.

Here's an instance of the argument being used predictively: http://autos.groups.yahoo.com/group/future-fuels-and-vehicles/message/5123

--- G.R.L. Cowan, H2 energy fan 'til ~1996
http://www.eagle.ca/~gcowan/boron_blast.html