Open Fuel Standard Act of 2009 or the OFS Act - Requires each light-duty automobile manufacturer's annual covered 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.
Extends limited liability protection to the use of fuel containing ethanol or renewable fuel in the operation of internal combustion engines by declaring that such fuel shall not be deemed to be a defective product or subject to a failure to warn due to such ethanol or renewable fuel content, unless it violates a control or prohibition imposed under the Clean Air Act.