Gas prices fall another penny
Retail gas prices drop for 33 days in a row, bringing the national average for regular gas down to $3.730 a gallon.
NEW YORK (CNNMoney.com) -- The price of retail gasoline fell for the 33rd consecutive day, according to a daily survey of gas station credit card swipes on Tuesday, which brought the national average down more than 9% from a record high hit last month.
The average for regular unleaded gasoline fell 1.1 cents to $3.730 a gallon from the previous day, according to the Daily Fuel Gauge Report from motorist advocacy group AAA and the Oil Price Information Service.
Retail gas prices hit a record high price of $4.114 a gallon on July 17. Gas prices are still nearly 35% higher than a year ago.
The average price of a gallon of gasoline has steadily ticked down on the back of falling oil prices. Crude futures hit a record high of $147.27 on July 11 but have since fallen nearly 24% amid concerns about weakening demand.
Ethanol: Faced with higher gas prices, many Americans have turned to ethanol to fuel their cars.
The price of E85, an 85% ethanol blend, fell to $3.041 a gallon on average from $3.051, AAA reported.
Corn-derived ethanol is cheaper than regular gas, but it is only readily available in the Midwest, where much of the nation's corn is produced.
Ethanol contains less energy than petroleum-based gasoline and burns less efficiently in flex fuel vehicles.
Drivers of vehicles capable of running on ethanol or gasoline would pay about $4.001 a gallon to get the same mileage from ethanol as from regular gas, according to AAA's estimates.
Diesel: The average price for diesel fuel, which is used in most trucks and commercial vehicles, fell to $4.373 a gallon from $4.387 the previous day, according to AAA.
The price of diesel has risen almost 50% in the last year. Because it is used in transporting goods, the rise in the price of diesel fuel has pushed up the prices of products and services.
State prices: Gasoline remains above $4 a gallon in only five states, according to the survey.
Alaska had the highest prices at $4.568 a gallon, down slightly from the previous day's price of $4.571. Hawaii was second at $4.423, followed by California at $4.030, Utah at $4.025 and Idaho at $4.002.
Missouri had the cheapest gas, with prices falling to $3.496 a gallon. Prices in South Carolina were the second lowest at $3.515, followed by Oklahoma and Tennessee at $3.529, and Arkansas at $3.549.
Drivers in Hawaii, the state with the most expensive diesel, paid an average of $5.309 a gallon for diesel. Diesel was cheapest in Missouri, where prices fell to an average of $4.088. 
