This came up on the Xebra mailing list, that in Washington State some legal change meant that three wheelers like the Xebra were being considered to be cars. But as a car that would clamp down their availability because they haven't been through DOT crash testing etc.
But it seems that a recently passed law clarified the status.
2009 Senate Bill 5482 (Modifying provisions for two- and three-wheeled vehicles)
Introduced by Sen. Mary Margaret Haugen, (D-Camano Island) (D) on January 23, 2009, clarifies definitions and regulations for two- and three-wheeled motor vehicles such as mopeds, motor scooters, and motorcycles.
Passed in the House (59 to 38) on April 9, 2009.