Premium gas is also often referred to as high-octane gas, thanks to an octane rating of 91 to 94. Regular gas typically has an 87-octane rating, and the 88-90 range is considered midgrade. While premium gas drives performance in certain engines, the idea that it's more fuel efficient is a myth. Any fuel efficiency gained would stem from engine performance and not the gas itself. Buying premium gas won't have you visiting a gas station any less frequently, especially with a standard engine that isn't designed to take advantange of premium gas.