This is interesting reading.
Federal, state, county, and local fuel taxes represent a significant portion of the price you are paying at the pump.
For example, your local Cumby in Providence might be charging
$2.31 per gallon at the pump. (
http://www.gasbuddy.com)
This price includes
$0.184 in federal excise tax
and
$0.31 in combined state taxes!
Without these taxes, gas at Cumby would be
$1.816 per gallon.
It would be even cheaper if we had one nationwide standard for clean air additives.
43 states have a fixed per gallon tax levy on gasoline and diesel. CT, FL,. KY, NE, NC, and WI have some kind of variable fuel tax, but it is still expressed in per gallon terms.
Here are some interesting stats from the API (American Petroleum Institute) - Adobe Acrobat required.
http://api-ec.api.org/filelibrary/mft070105.pdf