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Why filling up with the cheapest gas may not save you money

AAA says the current price for a gallon of unleaded is $3.45, up nearly 25-cents from a month ago.

MINNESOTA, USA — There's been a lot of talk about the cost of gas going up because of rising oil prices and the sanctions against Russia, but filling up with the cheapest gas might not always save you money.

In Minnesota, AAA says the average price for a gallon of unleaded is nearly a dollar more than it was a year ago.

Premium gasoline is $0.35 more and diesel is even more expensive. There's also flex fuel and ethanol blends to consider, only increasing the options for drivers. 

"It definitely can be confusing," said Dunwoody College Senior Auto Instructor Steve Cunningham. "You can put some thought behind it, but the manufacturer does a pretty good job at determining what fuel is correct for their vehicle."

Most drivers will use regular unleaded.

The higher octane rating, like premium, is for high-performance cars to prevent fuel from exploding and Cunningham says it doesn't benefit ordinary cars.

"That is a myth," said Cunningham. "Once you have a high enough octane for your engine to perform efficiently, anything more is spending extra money."

Then there are alternative fuels that mix gasoline with ethanol. Ethanol is made with corn, making it cheaper at the pump. However, ethanol has less energy, so you often have to fill up your tank more often.

"So, the biggest disadvantage is going to be drop in fuel economy," explained Cunningham, which he says could very well wipe out any of your savings.

However, experts say the benefits of ethanol blends include reducing greenhouse gases and dependence on fossil fuels.

For example, E85, which is 85% ethanol and 15% gasoline, is meant only for what's called "flexible fuel" vehicles. Often times, they come with a yellow gas cap to help you know whether yours is a flex fuel vehicle.

The E15, E20 and E30 blends can safely be used only if your vehicle was built after 2001.

Nearly all the gasoline in the country is already blended with some ethanol. In fact, Minnesota was the first state to mandate ethanol be used and requires any gas sold contain 10% ethanol.

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