The national average price for a gallon of diesel last week fell 3.8 cents to average $2.189, according to the Energy Information Administration.

All regions posted a decline, but California prices dropped the most, shedding 8.6 cents to $2.432. Despite this, California remained the most expensive region in which to fill up. In New England, prices held the steadiest, falling only 0.9 cents to $2.38. The cheapest region for diesel was the Midwest, at $2.129 on a 2.8-cent decline.