May 20, 2012 at 2:52 PM ET
According to the survey of some 2,500 gas stations in the continental United States, the national average for regular gasoline as of May 18, was down more than 12 cents a gallon compared with a year earlier.
It was the third straight survey to show a price decline. Prices fell 18.4 cents during the six week period, which survey editor Trilby Lundberg said was "enough" for consumers to feel.
San Francisco had the highest average price for self-serve, regular gasoline in the two-week survey period at $4.36 a gallon, while drivers in Memphis, Tennessee, paid $3.34, the least in the country.