The national average retail price of a gallon of diesel fuel fell 4.4 cents over the past week to $4.648.
This was after the average price remained unchanged the previous week.

It's still $1.813 more than it was a year ago. The highest average price was in the New England region at $4.833. The lowest was in the Gulf Coast region at $4.602.

Meanwhile, crude oil prices continue to be volatile. Disappointment that Saudi Arabia is not boosting production by more than 200,000 barrels a day sent oil prices higher Monday, reported the Associated Press. Light, sweet crude rose $1.38 to close the day at $136.74 per barrel on the New York Mercantile Exchange.

During a House committee hearing on Capitol Hill Monday, a hedge fund manager and oil company adviser testified that oil prices could quickly fall by half if Congress were to rein in speculators, reported CNNMoney.com.

At Barrons.com Monday, writer Andrew Bary reported that the price of oil may be peaking in the current range of $130 to $140 a barrel.

There is growing talk of an oil bubble, Bary wrote. "The trajectory of oil prices in the past eight years looks eerily similar to the Nasdaq's eight-year run to a peak of more than 5,000 in March 2000. More than eight years later, the Nasdaq is at half that level."