A UC Davis transportation expert has produced a better estimate of the dollar amount spent on U.S. military activities to ensure a reliable flow of oil from the Persian Gulf to American cars and trucks.

Mark Delucchi of the Institute of Transportation Studies (ITS-Davis) established that American taxpayers spent between $27 billion and $73 billion in 2004 (the most recent year with data available) on military protection of our oil interests in the Persian Gulf region.

The portion of that specifically attributable to the use of gasoline and diesel fuel amounts to about 3 cents to 15 cents per gallon.

Delucchi said the estimate should be useful to analysts helping the incoming Obama presidential administration and Congress to develop public policies on energy and transportation fuels.

"Wise, robust energy policy takes into account both the 'private cost,' which is the monetary value of the fuel at the pump, and 'social costs,' which are the monetary value of the social impacts of acquiring and using that fuel," Delucchi said.

"This sort of information is essential when government tries to figure out, for example, what the ideal price of a transportation fuel or vehicle might be, or when we want to compare the value of vehicles powered by gasoline with vehicles powered by electricity."

Delucchi, an authority on energy, environmental and economic analyses of transportation systems, wrote the analysis with James Murphy, an economist who earned his doctorate at UC Davis and now holds the Rasmuson Chair of Economics at the University of Alaska at Anchorage.

The study, titled "US military expenditures to protect the use of Persian Gulf oil for motor vehicles," was published in June in the peer-reviewed journal Energy Policy.