Open Fuel Standard Act of 2008 or the OFS Act - Amends federal transportation law to require each light-duty automobile manufacturer's annual inventory to comprise at least: (1) 50% fuel choice-enabling automobiles in years 2012-2014; and (2) 80% fuel choice-enabling automobiles in 2015, and in each subsequent year.
Defines "fuel choice-enabling automobile" as: (1) a flexible fuel automobile capable of operating on gasoline, E85, and M85; or (2) an automobile capable of operating on biodiesel fuel.
Authorizes a manufacturer to request an exemption from such requirement from the Secretary of Transportation.
Requires: (1) each manufacturer that receives an exemption to place a label on each exempted automobile; and (2) each exempted light-duty automobile delivered to a dealer and first purchaser to be accompanied with a written notification of such exemption.