If I'm honest I'm not sure I get the private plate thing. I've known people putting personal plates on cars to hide the year but the meaningless and obscure leave me cold. If it doesn't spell your name then don't try and make it up with numbers and badly placed fixing screws. A link to the vehicle is fine, ish. Anything that's not obvious looks desperate. Just put an M on your 320 BMW, it amounts to the same.
