I had a plate that read I8A BMW on a 5-speed SHO. Lots of Bimmer owners didn't like that. I suppose that doesn't help. How about MMUNICH? Or just E39M5 -- that's subtle -- assuming its a '98 or so -- and that chassis code is correct.
duno if colorado would let you - but a variation that you might like:
AMGSUKS
to explain it to them so you can use it:
It stands for "American Games: United Kingdom Silver" and tell them that its in honor of your friend __________ who won a silver metal at the last panamerican games . . .
A good story will most likely get you an "offensive" plate.