STANG2K5...yes, it could only be owned by one person in your state...obviously you. However, as with all vanity plates, they are only exclusive in ownership within the state they are registered in. There could easily be 49 others across the country, that might soon make the same claim.
I suspect too, that someone else will soon own (the reverse) 2K5STANG...which would basically represent the same thing. Then there's the upcoming '06 owners...
In any case, I like it. As you can see by my screename, I did a similar thing using roman numerals to reference my 1976 Cobra, even though my license plates are something different altogether.
Here's a few using that thinking, some '05 owners might consider:
MMV-GT
MMVSTANG
MMVPONY
and my personal favorite:
NOIUP-V6