Revises the definition of "commercial motor vehicle" with respect to federal commercial motor vehicle safety laws to include a vehicle with farm-designated license plates engaged in the transportation of agricultural commodities or farm supplies, or a vehicle controlled by a farmer and used to transport such items to or from a farm, having a gross vehicle weight rating or gross vehicle weight the greater of which exceeds the minimum weight of a commercial motor vehicle as established by the state. (Current law applies to vehicles having a gross vehicle weight rating or gross vehicle weight of at least 10,001 pounds, whichever is greater.)
Prohibits the Secretary of Transportation from withholding commercial motor vehicle safety improvement grants from a state solely because it authorizes drivers of farm vehicles having a gross vehicle weight of between 10,000 and 26,001 pounds to operate without complying with federal commercial motor vehicle safety laws.