Economists promote energy taxes as cost-effective. But policymakers raise concerns about their regressivity, or disproportional burden on poorer families, preferring to set energy efficiency standards instead. I first show that in theory, regulations targeting energy efficiency are more regressive than energy taxes, not less. I then provide an example using data on automobiles in the United States. Taxing gas would be less regressive than regulating the fuel economy of cars if the two policies are compared on a revenue-equivalent basis.