The average price for a gallon of diesel nationally fell 1.6 cents to $2.58 for the week ending December 31, according to the Energy Information Administration.
Prices fell in all regions, with the biggest decline in the Central Atlantic (2.9 cents to $2.681). The cheapest region was the Gulf Coast, at $2.50 after a 1.4-cent drop. California remained the most expensive region ($2.883), even though it had the smallest decline at 0.2 cents.