The differences between gasoline brands are the gasoline detergent additives they use and the amount of ethanol in the gasoline. All gasoline must meet the minimum detergent additive requirements set by the Environmental Protection Agency. Top-tier gasoline meets a higher additive standard that was developed by several automakers.
While top-tier gasoline has additional additives that can improve performance, the EPA's minimum requirements ensure that all gasoline sold in the United States is safe to use. Drivers should check their owner's manuals for gasoline recommendations if they want to make sure they get the best performance.
A list of top tier gasoline brands is available on TopTierGas.com, as of 2015. To view the list, visit the site's home page and click Retailers.