> The stickers are cut vinyl and there is No background.

I see!  Then the yellow would make more sense since it would
show up better agains the tinted windows.

2 yellow stickers then.

Reflective yellow cutout perhaps?  That would be so cool even if
it  cost a little more - easier to sport list members leaking
coolant at night at the side of the road <-- kidding about the
coolant!

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Chris S.'85 Westy Camel -> http://www.knology.net/~vw/vws/camel/ '84 Westy Hershey -> http://www.knology.net/~vwghost/hershey/ '01 NB TDI -> http://www.knology.net/~vw/Beetle.jpg