AAA: Premium Gas Not Worth the Money in Cars that Don’t Require It

Premium gasoline is getting more expensive yet provides little or no benefit in vehicles for which it’s recommended but not required, according to a new study by AAA.

Such vehicles are unlikely to see any efficiency or performance improvements from premium gasoline (91 octane or higher) during typical city or highway driving, AAA says.

The insurance giant/auto club did find that high-octane fuel provides a 3% improvement in fuel economy and a 1% bump in horsepower in tests that simulated extreme driving conditions, such as towing, hauling cargo and aggressive acceleration.

Last year, nearly 1.5 million new vehicles sold in the U. S. recommend, but don’t require, premium gasoline. AAA in conjunction with the Automobile Club of Southern California tested six such models with a range of engines: an Audi A3 (1.8-liter 4-cylinder), Cadillac Escalade (6.2-liter V-8), Ford F-150 ( 3.5-liter V-6), Ford Mustang (5.0-liter V-8), Jeep Renegade (1.4-liter 4-cylinder) and a Mazda MX-5 Miata (2.0-liter 4-cylinder).

Since 2010, the price gap between premium and regular-grade gasoline has risen from about 10% to more than 20% or more per gallon, according to AAA. It notes that drivers can select from regular 85-octane to super-premium 94-octane (or higher) depending on the area of the country and gasoline station.

Past AAA research has shown no benefit in using premium gasoline in vehicles in which premium fuel neither required nor recommended. But the group says more than 16.5 million U.S. drivers of such vehicles did so anyway in 2015, wasting nearly $2.1 billion on the higher-priced fuel.

Drivers of vehicles that require premium gasoline should always use the fuel, AAA says. The organization also recommends that any vehicle that makes a “pinging” or “knocking” sound while using regular gasoline should switch to a higher-octane fuel.