here's some more i just found
2MCHHP Too much horsepower, spotted on a Chevy SS
4 3 2 1 GO on a Nissan Twin Turbo 300zx
4U2NV For you to envy
6DRYV Sex Drive
6HORM1 Sex hormone
88 MPH On a Graphite Volvo 240DL. A reference to the speed you need to achieve in order to time travel (Back to the Future)
ARETE Greek for "excellence"
BCNU2 Be seeing you too
BIG BUX On a Ferrari 308
BZNU Be zeeing you, on a 280Z
BY BY COP On a Ferrari F40
CU N QRT See you in Court, on an attorney's car
DJAKEL "The Devil" in Swedish, and it is on a Red Saab 900 Turbo Convertible.
FASTER
FLY-BY On a '91 Steath
GGGGGGG G-string, get it? Seen in San Francisco
GROWL On a Jaguar
GR8TTS Seen in California 10 years ago...enuff said...*blush*
H15 EGO On a Porsche
HIHO AG Hi ho silver! your car is silverish
HUMR ME Humor me
I8AV8 I ate a V8!
IB6UB9 I be 6, you be 9...enough said
IONO1 I owe no one
KEEP UP Yeah, you slow poke!
LETS M8 Let's mate
PULN GS Pulling Gs, on a 300ZX
RUNVUS Are you envious?
ST ETR Street eater
URNZWA You heard him, "You are in zee way!"
XCLER8 Accelerate
V8KILR
XTREME and that your car is!
YBNRML Why be normal
YOT YM My toy, mirror image
Y TRY Why try to catch up? Don't even bother!
YRUMAD Why r u mad, seen on a ZR1