LOS ANGELES (CNS) — American motorists wasted more than $2.1 billion in the past year by spending extra for premium gasoline in vehicles designed to run on regular fuel, according to a AAA study released Tuesday, Sept. 20.

“AAA’s tests reveal that there is no benefit to using premium gasoline in a vehicle that requires regular fuel,” said Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center. “Premium gasoline is specifically formulated to be compatible with specific types of engine designs and most vehicles cannot take advantage of the higher octane rating.”

The Auto Club tested a variety of vehicles with different types of engines, comparing their performance when fueled with regular and premium gasoline in varying driving conditions. The vehicles were tested on measures including horsepower, fuel economy and tailpipe emission, and investigators found “no significant increases in any tested category.”

John Nielsen, AAA’s managing director of Automotive Engineering and Repair, said many drivers assume that “premium” gasoline is somehow better for their vehicle.

“When it comes to gasoline, ‘premium’ does not mean ‘better’ if your vehicle doesn’t require it,” he said. “Drivers looking to upgrade to a higher quality fuel for their vehicle should save their money and select a ‘Top Tier’ gasoline, not a higher-octane one.”

According to the study, 70 percent of U.S. drivers own vehicles that require regular gasoline, 16 percent have vehicles that require premium fuel, and 14 percent require mid-grade gas or use alternative energy.  In the last year, 16.5 million drivers needlessly used premium-grade gasoline in their vehicle at least once, and on average, those drivers did so at least once a month.