John Travolta's Vintage Car Stolen

Law enforcement sources tell us Travolta had parked his 1970 Mercedes-Benz 280SL on the street -- just a couple blocks from a Jaguar dealer.

We're told John was only in the dealership for about 10 minutes -- and when he returned ... his whip had vanished.

John went back to the Jag dealer and waited for police to show up to take a report. We're told there are no witnesses ... at this point.

By the way ... that Benz can sell for as much as $100,000.