Is premium gasoline worth it?

(CBS) -- David Desovino drives a 17-year-old Saturn and has never even considered paying for premium gasoline.

"I have no problems with regular gas, it's fine," he says.

While he doesn't use premium, AAA says 16.5 million U.S. drivers do and they're wasting their money. The organization tested regular and premium gasoline in vehicles that recommend but don't require the highest level fuel. It found premium only offered a 2.7% improvement in fuel economy and a 1.4% increase in horsepower.

"For those drivers whose vehicle only requires regular or mid-grade gas, higher octane fuel is not going to benefit them on the road," says Tamra Johnson with AAA.

Cost is another big consideration. At a gas station in New Jersey, premium is $3.19 a gallon, 58 cents higher than regular.

According to AAA, U.S. drivers unnecessarily spent $2 billion last year alone on premium gas. Johnson believes drivers are confused because more automakers are recommending the higher octane fuel.

"That's really the result of automakers being held to more stringent fuel economy standards," she says.

The auto group says the only cars that truly benefit are the ones that require higher octane gas like Carl Legreca's Audi.

"For a $50,000 car that I don't want to replace, I put the best gas in," Legreca says.

But if you're one of the millions of drivers who don't need it, AAA says save your money.