Just as the Big Three automakers talked of collapse and begged Congress for additional aid, the prices of both gasoline and crude oil tumbled to four-year lows this week.

January crude oil futures fell less than $42 per barrel early Friday morning while unleaded gasoline traded below 93 cents per gallon. Oil's plunge from more than $147 per barrel in July stems from concerns about the severe decline in domestic and global demand and from OPEC's inability to reach a decision to cut production.

Reports that the cartel is producing 500,000 barrels per day above its current quota and stories of tankers being chartered for use as floating storage added to the near panic selling throughout the week.

In a bizarre development which began in October, the price of gasoline on a per barrel basis has dropped below the price of the crude oil from which it is made. Refined unleaded gas this week traded about $4.50 per barrel below the price of West Texas crude oil for the first time, meaning refiners are losing money as they sell their product.

The downward spiral in corn, wheat, and soybeans continued this week as grain prices are also dependent on energy costs. Grain prices were down on average about 6 percent month-to-date. The next Department of Agriculture supply/demand report will be released Thursday and will tell us more about the stockpiles of U.S. grains and will probably continue to show problems with declining exports.

Cheap gasoline and diesel prices also push ethanol and biodiesel lower, further hurting the markets for corn and soybean oil. January ethanol is now trading less than $1.50 per gallon.

Buyers were also hard to find this week in the livestock markets as cattle and hogs fell to new two-week lows, and demand continues to be threatened by fears of recession and unemployment.

Rice prices were the only market to buck the trend this week with January rice hitting limit up on Thursday on expectations that this year's crop will be smaller than expected. January rice traded at 13.86 cents per pound on Friday's opening.

Opinions expressed solely are those of the writer. Walt Breitinger is vice president of commodities at Wachovia Securities. He can be reached at (219) 738-6460.