Why don EPA fuel economy tests use ethanol-blended gasoline now that most gasoline contains ethanol?
EPA fuel economy tests are conducted according to Federal testing regulations which require 100 percent gasoline. These regulations could to be changed, but changing them would be somewhat problematic. While it is common for gasoline pumps to allow for up to 10 percent ethanol, the actual amount of ethanol blended into the gasoline varies greatly, and fuel blending requirements vary by state. Changing the test methods would also make it difficult to compare vehicles tested with ethanol blends with those tested with straight gasoline. So, without a national standard for blended regular gasoline and a Federal mandate to change the test fuel used, the EPA will not change the test fuel.
