Ray J -- Princess Love Is Gonna Be Pissed ... I Got HER Car Towed (VIDEO)

Ray J's fight over his breakfast tab was more serious than we thought, because it turns out it wasn't HIS car he got towed ... it was his girlfriend's, and the key to her luxury ride is STILL missing.

As we reported, Ray J had a dispute with the staff at Kitchen24 over his bill, and cops were called -- but what we couldn't figure out was why a tow truck got into the whole mess.

Short story, long -- Ray J left the key fob to Princess Love's Mercedes-Benz in the restaurant when he left, but was still able to start the car and drive off. It has one of those fancy key-less starters, and the car was close enough to the restaurant that it started.

Everything went downhill after that ... ending with AAA taking away the Benz.

Listen to Ray's explanation. Two things are clear -- 1. He thinks someone in Kitchen24 still has his key, and 2. Princess Love is gonna tear him a new one.