And since 2014, the EPA has regulated that all diesel sold and produced in the United States must be ULSD (ultra low sulfur diesel) -- a standard of diesel which limits sulfur contents to 15 parts per million. Sulfur content regulations have reduced toxic emissions by at least 90%, according to the EPA.

The EPA's regulations greatly benefit the environment. But lowering the sulfur content of diesel has led to lower energy density (less fuel economy per gallon) and raised production costs at the refinery, placing upward pressure on prices.

President Joe Biden's administration recently called on Congress to suspend the federal tax on diesel and gasoline. Regardless of whether the proposed tax holiday would be effective, it calls attention to the tax itself.

The federal motor fuel excise tax, which has not changed since 1993, imposes an extra 18.3 cent tax on gasoline and a 24.3 cent tax on diesel. Revenue from the tax supports the Highway Trust Fund, a federal purse that finances the construction and maintenance of highways and other mass-transit projects.

And since 2014, the EPA has regulated that all diesel sold and produced in the United States must be ULSD (ultra low sulfur diesel) -- a standard of diesel which limits sulfur contents to 15 parts per million. Sulfur content regulations have reduced toxic emissions by at least 90%, according to the EPA.

The EPA's regulations greatly benefit the environment. But lowering the sulfur content of diesel has led to lower energy density (less fuel economy per gallon) and raised production costs at the refinery, placing upward pressure on prices.

President Joe Biden's administration recently called on Congress to suspend the federal tax on diesel and gasoline. Regardless of whether the proposed tax holiday would be effective, it calls attention to the tax itself.

The federal motor fuel excise tax, which has not changed since 1993, imposes an extra 18.3 cent tax on gasoline and a 24.3 cent tax on diesel. Revenue from the tax supports the Highway Trust Fund, a federal purse that finances the construction and maintenance of highways and other mass-transit projects.