EXITING THE HIGHWAY ON AN OVERPASS BRIDGE THE ENGINE STOPPED WITHOUT WARNING AND WOULD NOT RESTART. A FEW MOMENTS LATER SMOKE WAS VISIBLE FROM UNDER THE DIRECT IGNITION COVER AND SMALL FLAME WAS APPARENT. THE FLAME WENT OUT AFTER A FEW MOMENTS. HOWEVER, WE WERE LEFT STRANDED ON AN UNLIT BRIDGE OVERPASS THAT WAS UNDER CONSTRUCTION AT DUSK (WITH AN INFANT AND TODDLER). SAAB ROADSIDE ASSISTANCE WAS CONTACTED (THEY SUGGESTED WE WAIT WITH THE VEHICLE FOR APPROXIMATELY AN HOUR UNTIL A TOW TRUCK COULD REACH US.) THIS INCIDENT FOLLOWS A STRING OF MINOR ELECTICAL / ELECTRONIC "BUGS" IN WHICH ERRONEOUS SIGNALS ABOUT LIGHT FAILURES WERE DISPLAYED AND THE HEADLIGHTS FAILED TO TURN OFF WHEN THE KEY WAS REMOVED (THIS IS AN AUTOMATIC FEATURE ON SAABS).*AK