An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Fuels Registration, Reporting, and Compliance Help

When will EPA publish a corrected version of the Complex Model? The NOx equation corrections published in the DFRM were not correct, and the published evaporative VOC equations do not yield the published baseline emissions for baseline fuel.

Errors in the final rule for the reformulated gasoline program and the DFRM are being corrected in an upcoming technical amendment.

The spreadsheet version of the Complex Model does not contain the errors that appeared in the Federal Register description of the Complex Model. However, the equation coefficients in the spreadsheet have been rounded in comparison to the coefficient values given in the Federal Register.

This difference results in a disparity of less than 0.005% between the published baseline emission values and the values calculated from the evaporative equations in the spreadsheet, a disparity which is unlikely to affect any results. Nevertheless, EPA will update the spreadsheet version of the Complex Model as soon as time permits.(10/31/94)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)