The national average price for a gallon of diesel dropped 4.9 cents to $2.546 for the week ending Oct. 1, according to the Energy Information Administration. That marked the seventh consecutive week of price drops.

All regions reported a decline in prices, but the steepest was seen in the Rocky Mountain region where prices plummeted 14.8 cents to $2.679. Prices were the most stable in the Lower Atlantic region, falling only 2.3 cents to $2.503.

The cheapest region in which to fill up is the Midwest, where prices are $2.467. California once again holds the dubious honor of being the most expensive region in which to fill up, in spite of a 7.5-cent drop to $2.835.

For more information, go to http://tonto.eia.doe.gov/oog/info/wohdp/diesel.asp