Diesel is down another 5.2 cents per gallon from last week, a 7.4-cent drop from a high of $2.616 on June 22
, according to the Department of Energy. This is the largest one-week drop since the price started falling three weeks ago.

Trucking's main fuel landed at a national average of $2.542, which is $2.222 lower than the same week last year, when prices hit a high of $4.764. Prior to the declines, diesel had climbed 43.1 cents from May 4 through June 22.

Diesel supplies were up 1.8 million barrels to 113.4 million during the week ending July 3, according to the Energy Information Administration. During the same week last year, inventories were up 21 percent.

According to a Short-Term Energy Outlook released last week by the EIA, analysts expect diesel to average $2.61 per gallon this quarter, up 29 cents from the second quarter. For 2009 and 2010, analysts project the fuel to average $2.46 and $2.79, respectively.

The Gulf Coast and Lower Atlantic regions saw the lowest prices this week, dipping down to $2.494 and $2.508, respectively. California led the pack with the highest prices in the nation at $2.727, followed by the Central Atlantic region with $2.663.

Diesel was not the only thing to fall Monday, as U.S. crude oil delivery for August slipped 20 cents to $59.69 per barrel. That's on the heels of last week's decrease of 11 percent, according to Reuters. Prices dropped to the lowest in almost two months as a result of global economic woes, Reuters reported.

The Short-Term Energy Outlook predicts crude oil prices to increase through the end of the year as well as next year, averaging about $60.35 for 2009 and $72.42 for 2010.

Meanwhile, gasoline prices also slipped Monday, going down 8.4 cents to an average of $2.528. This was a larger drop from last week, when the price was down 3 cents to $2.612.