Here are the answers to the questions we get asked the most. Check back for updates.

Q: Is the E85 I am getting from the pump consistent? Does it contain atleast 85% ethanol?

A: The 85 in E85 refers to the maximum ethanol content; In the case of E85, as defined by ASTM D5798-14, the maximum allowable ethanol content is 85% with the remaining 15% being the gasoline. Furthermore, pure ethanol is not used in the production of E85; denatured fuel ethanol is used, which is already diluted by 2%. Therefore, the true maximum ethanol content of E85 is actually 83%. This being said, the allowable minimum ethanol content is a lot more interesting and relevant when dealing with engine tuning. As of today, the minimum ethanol content allowable and still be within specification is 51%. Your E85 pump gas could contain as low as 51% ethanol.

Source: Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines