From Rap Dictionary
interjective
5000
A farewell bidding, from "I'm outta here", which evolved to "I'm Audi", and to 5000" after the Audi 5000 car, which got recalled and is a rare sight nowadays. "Yo, we outta here, 5000, G!" -- Ice Cube and Flavor Flav (I'm only out for one thang [1990]).