Millions of drivers are wasting money on premium gasoline, according to a new study from AAA. Don Redman with AAA says over 16 million drivers are putting higher octane gas in their cars, and paying more for it, when their vehicle doesn’t need premium gas.

“We’ve calculated about $2.1 billion are wasted annually by motorists who are putting in premium gasoline in a vehicle that only requires regular gasoline,” Redman said.

Redman says they encourage people to check their car’s owner’s manual to see what kind of gas their car requires. He says 70% of vehicles on the road just need regular gas.

“If your car takes regular unleaded gasoline, there’s not benefit to putting in premium gasoline, and all it does is end up wasting your money,” Redman said.

Redman says some high end vehicles do require premium gas because of the way the engine is calibrated. He says the only differences between regular and premium gas are the octane levels and the price.

“Regular gasoline is about $2.21 right now nationally. Premium is $2.71. So you’re talking about a 50 cents per gallon difference,” Redman said.