Gas stays below $4 for second straight day
Gasoline prices declined for the 10th straight day, staying below the $4 mark for the second day in a row.
NEW YORK (CNNMoney) -- Gas prices declined for the 10th straight day, staying below $4 a gallon, according to a nationwide survey Sunday by motorist group AAA.
Gasoline: The price of regular unleaded gasoline dropped a penny to $3.970 a gallon on average, according to AAA's daily survey of credit card swipes at filling stations.
Americans have seen their pocketbooks stretched thin on the back of record high fuel prices and the churning economy. Gas prices have stayed above $4 for nearly two months, having first crossed the mark on June 7, when prices hit $4.005 a gallon.
Surging oil prices kept gas on an upward trajectory, with prices hitting a record high of $4.114 on July 16. Prices stayed there for two days before starting to retreat.
Ethanol: High fuel prices have caused many drivers, particularly those in states with strong agricultural industries, to switch to ethanol. The price of E85, an 85% ethanol blend, which burns cleaner than pure gasoline and is made primarily from corn, edged higher to $3.240 a gallon from $3.231. While ethanol is derived from renewable sources, it is less efficient than gasoline. Subsequently, a car running on E85 would pay the equivalent of $4.264 per gallon to get the same mileage as gas, the AAA survey estimated.
Diesel: The average price of diesel fuel, which is used to power most trucks and commercial vehicles, fell to $4.748 a gallon to $4.757, according to the AAA survey. Diesel remains more than 60% higher than last year. Because of its use in transporting goods, high prices for diesel have affected the prices of other items. 
