Oil prices sank to their lowest point in weeks Friday as investors questioned whether crude has cooled enough to reflect a serious deterioration in demand. Prices at the pump eased to nearly $4 a gallon and the AAA auto club said that could drop another quarter by Labor Day.

Light, sweet crude for September delivery fell $1.60 to $123.89 a barrel in on the New York Mercantile Exchange. Earlier the contract dropped as far as $122.50, its lowest point since June 5.

In another sign that Americans continue to struggle with soaring energy prices, filling station operators hungry for business ratcheted down the average price for a gallon of regular by 2 cents, according to auto club AAA, the Oil Price Information Service and Wright Express.

AAA spokesman Geoff Sundstrom said such a large decline indicates a deteriorating demand by the world's thirstiest oil consumer. Retail prices have fallen about a dime per gallon in just the past week.

"People say typically prices shoot up like a rocket, fall like a feather. But this time ... it looks like it's different," Sundstrom said. "The retail sector is interested in bringing these prices down as fast as they can to stimulate business in their convenience stores."

A gallon of gas now sells for $4.006, the first time it has been that low in nearly seven weeks. Diesel dropped nearly a penny and a half to $4.774 a gallon.

Sundstrom said prices at the pump should slip below the $4 mark over the weekend and could drop by at least another 25 cents by Labor Day, if oil stays on its downward path.

"We're seeing a historic change in driving habits," he said, although he added that "we still have a long way to go before we get back to the comfort zone, if you will, for the consumer."

Oil traders managed to post a gain of $1.05 a barrel Thursday, but analysts say the market's momentum points to further declines. Crude has fallen in six of the past eight sessions, and is trading more than 15 percent below its peak above $147 a barrel earlier this month.

By afternoon Friday, crude was down nearly 16 percent from its peak above $147 a barrel two weeks earlier. Still, prices remained about 65 percent higher than they were this time last year.