Will is still FUMING about his ultra-rare, super-expensive, incredibly-hideous custom car ... claiming his $700,000 ride is still missing ... despite what his publicist is telling the media.

We broke the story ... Will claimed his car was "stolen" after a party in Hollywood this week ... insisting he left it with the valet at Bardot nightclub but when he went to get it back, the car was nowhere to be found.

The next day, we reached out to Will's publicist, Sallie Olmsted, and asked about the car ... she wrote back insisting, "Everything is fine, he has his car."

Hours later, Will went on Twitter and COMPLETELY REFUTED his publicist's claim ... saying "my car is still m.i.a."

Confused by the contradicting statements, we reached out to Will's rep ... who told us, "I wasn't on site at the time, but all is fine now."