Actually, reading through the copyright office's website I get this under examples of copyrightable material: "Weaving designs, lace designs, tapestries" I don't really see how that is much different than a distinctive paint job so maybe you can copyright it after all. Still--I kind of think it's by nature a trademark like Eddie's stripes or Zachckkkchk's bullseye. But that might be not legal.
Quick, fetch me a lawyer! We'll straighten this out....
(And you're from Australia. Man, my head really wasn't in this discussion.)