Filling up this weekend may be cheaper than you'd think.
Many tipsters on the Internet suggest avoid buying gas on Friday, Saturday or Sunday, as stations may raise prices for the weekend rush. But the Association for Convenience and Fuel Retailing (NACS), which represents 80 percent of the nation's fuel stations, says that's not true. Waiting until midweek to fill up won't necessarily save you money.
With retail gasoline prices falling steadily for the past week, "many stations may actually cut their prices on the weekend to keep up with the competition," said NACS spokesman Jeff Lenard. Of course if the trend of lower gas prices continues, the longer you wait, the cheaper the fuel may be when you finally pull in to a station.
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Gas prices have fallen about a penny a day for seven days, bringing the national average for regular gasoline to $3.21 a gallon Friday, according to AAA. That's the lowest national average price for this time of year in three years.
According to GasBuddy.com, the average price of regular gasoline is under $3 a gallon In eight states (Missouri, Oklahoma, Arkansas, Texas, Kansas, Nebraska, Louisiana and New Mexico).
Where can you find the cheapest gas? Drivers in Tulsa, Oklahoma were paying as little as $2.78 a gallon for the regular grade on Friday, according to GasBuddy.com, as states in the south-central part of the U.S. have the lowest gas prices in the nation.
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AAA spokesman Michael Green says high gas prices in California and Hawaii are likely to prevent the national average from dipping below the $3-a-gallon mark this year. Drivers in Santa Barbara and Honolulu were paying just under $4 a gallon Friday.
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AAA predicts the national average price of gasoline will be about $3.10 a gallon by the end of 2013.
—By CNBC's Sharon Epperson. Follow her on Twitter: @sharon_epperson.