Diesel prices dropped 4.9 cents to $4.086 and gasoline also declined, marking the first downturns for both fuels in 12 weeks, the Department of Energy reported to NASSTRAC yesterday. Gasoline prices decreased 5.2 cents to $3.826 a gallon, DOE said Monday following its weekly surveys of filling stations. Despite the downturns, diesel prices are now 30 cents higher than the same week last year, while gasoline is 31.7 cents more expensive than a year ago. The diesel decrease was the biggest since June 25, when it fell 5.1 cents. Gasoline fell 8.1 cents in its last decline, on July 2. Diesel had risen 48.7 cents in the previous 11 weeks of increases, while gasoline rose 52.2 cents, according to the DOE.