What’s in your gasoline? Understanding U.S. motor gasoline formulations ›

Motor gasoline in the United States is a blend of hydrocarbons and chemicals, with specific formulas varying by region and season. To meet federal air quality standards, the U.S. Environmental Protection Agency (EPA) and state regulators require different formulations, depending on air quality and location, which affect performance, cost, and emissions. In addition, warmer summer months require a different gasoline formulation than cooler winter months. Key differences between formulations include octane rating, volatility—commonly measured as Reid vapor pressure (RVP)—and emissions. This year, the EPA will relax federal enforcement of summer RVP standards to help reduce gasoline prices. More ›

Data source: U.S. Environmental Protection Agency