The price drop has led to a near free fall in gasoline prices in the United States. On Monday, the national average price for regular gasoline was $3.20, 9 cents lower than it was a week ago and 14 cents below the price a year ago, according to the AAA motor club.

The price at the pump generally follows oil after a few days, leading energy experts to predict lower prices for the rest of the month at least.

"This is not your garden variety autumn price decline," said Tom Kloza, chief oil analyst at GasBuddy.com, which reports fuel prices from filling stations across the country. "Clearly there is a rift in OPEC, and that means we are more likely to see a price war over the next six months. Crude oil is teetering on the brink of collapse."

Mr. Kloza predicted that the national average for regular gasoline was headed to between $2.95 and $3.10 a gallon. The average household consumes 1,200 gallons of gasoline a year, translating into an annual savings of $120 for every 10-cent drop in the price of gasoline.