U.S. consumers wasted billions of dollars last year filling their cars with costly premium-grade gasoline for no tangible benefit, according to a study by the country’s leading motorist advocacy group. The report by Heathrow, Florida-based AAA comes as low pump prices and a growing economy enticed U.S. motorists to buy more premium-grade gasoline in June than in any month since 2003, according to the U.S. Energy Information Administration. While an overwhelming majority of cars on U.S. roadways are designed to consume regular gasoline, the study found that motorists still use premium-grade in the hopes of achieving more horsepower and better fuel economy. As a result, U.S. drivers spent an estimated $2.1 billion extra by using premium gasoline in vehicles designed for regular fuel. Premium provides little or no benefit to cars designed to run on lower octane, regular gasoline, the study said. “Drivers see the ‘premium’ name at the […]