As I understand it, the CSF tags are still good on the Dulles Toll Road (267), although I'm rarely on it during rush hour, and they're still good in Hampton Roads (64/264), where I've only ever been once in the 19 years I've lived near DC. No mention of the 495 express lanes, which I'm guessing means no good.
Also, the Clean Fuel graphic is in the center of the newest plate, so it would break up my mirror image idea: [ ZAJ <> Z3T ] ...and yes it's only 6 characters max.