Yes Willbd...I think you're right. It is confusiing however. In the Washington State regs they mention that any AFV must have a placard. They include biodiesel in their AF sections mentioning tax incentives etc., but when you go the the specific regulation, it says AF does not include gasoline or diesel. Doesn't specifically say biodiesel, but it does say diesel. I guess we can assume biodiesel is the same as diesel in this regulation. This is the reg below...

<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD vAlign=bottom>RCW 46.37.467

Alternative fuel source — Placard required.

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</B>(1) Every automobile, truck, motorcycle, motor home, or off-road vehicle that is fueled by an alternative fuel source shall bear a reflective placard issued by the national fire protection association indicating that the vehicle is so fueled. Violation of this subsection is a traffic infraction.

(2) As used in this section "alternative fuel source" includes propane, compressed natural gas, liquid petroleum gas, or any chemically similar gas but does not include gasoline or diesel fuel.

(3) If a placard for a specific alternative fuel source has not been issued by the national fire protection association, a placard issued by the chief of the Washington state patrol, through the director of fire protection, shall be required. The chief of the Washington state patrol, through the director of fire protection, shall develop rules for the design, size, and placement of the placard which shall remain effective until a specific placard is issued by the national fire protection association.