This letter provides revised EPA assigned deterioration factors (ADFs) for determining compliance with chassis-based exhaust and evaporative mission standards. These assigned deterioration factors may be used for small volume manufacturers under the provisions of 40 CFR 86.1826-01, and are applicable for chassis tested vehicles using petroleum-based fuels (gasoline and diesel), alcohol fuels (ethanol and methanol) and gaseous fuels (natural gas and liquified petroleum gas).
