Downgrading gasoline could cost motorists more

According to AAA, the national average price of regular unleaded gasoline is $3.92 per gallon, while the average cost of premium gasoline is $4.19 per gallon.

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"It hits deep in my pockets," said Tanya Powell, who commutes every day from Garner to Raleigh.

She has recently made a change from unleaded plus to regular grade gasoline to save some change.

But auto experts say that while it might save motorists money now, it will cost them in the long run.

For example, using regular gasoline to fill up a Mercedes-Benz would save an average of approximately $4 on a tank of gasoline.

But the recommended grade is minimum 91 octane for a reason, says Steven Lewis, a technician at Leith Mercedes-Benz of Raleigh.

"It will start to rattle or knock. It will make noise and especially under acceleration or heavy loading," Lewis said. "It's not responding like it should."

Lewis said the higher-end automobiles have more powerful engines that require premium fuel for peak performance.

Drivers might be able to get by with lower octane gasoline a few times, but they will actually get fewer miles per gallon, he said. That would defeat the purpose of switching to a lower grade.

"You're only hurting your fuel economy and power output as a result of that," he said.