Premium gas is a type of gasoline with a higher octane rating than regular gas. The octane rating is a measure of the fuels ability to resist "knock," which is the loud noises that occur when the air/fuel mixture is incorrect. Premium gas is generally considered any type of gasoline with an octane level of 91 or greater, with 91 octane and 93 octane being the most common versions of premium gasoline available at gas stations in the United States. Premium gas is typically used in high-performance engines, such as those found in luxury or sports cars, that require higher-octane fuel to operate optimally.

If your car does not recommend premium gas, you arent doing your vehicle any favors by getting it. Some vehicles specify "premium" gas because certain kinds of engines operate optimally with higher-octane fuel. If your owners manual doesnt call for premium gas, your vehicle doesnt need it. Mixing premium and regular gas in your car or truck is okay, and modern vehicles high-tech electronics and fuel monitoring features easily adjust to different grades of gasoline. However, if your vehicle owners manual suggests using premium gas, its important to follow that recommendation to maintain all-important things like performance and fuel economy levels.