NOTED A SPONTANEOUS FUEL SMELL IN CABIN BEHIND DRIVERS SEAT AFTER RETURNING TO PARKED VEHICLE. AT FIRST ASSUMED THAT THE TANK MAY HAVE BEEN OVERFILLED. THE STRONG FUMES PERSISTED IN THE CABIN AND ALSO WHEN APPROACHING THE VEHICLE UNTIL THE FUEL TANK EMPTIED BELOW THE 1/2 MARK. BROUGHT VEHICLE TO CHEVY DEALER JUST BEFORE WARRANTY EXPIRATION. I WAS TOLD IT WAS LEAK TESTED AND THEY COULD NOT FIND ANY LEAK. I HAVE SINCE TAKEN IT TO X3 INDEPENDENT MECHANICS SPENDING OVER 600.00 AND NONE HAVE BEEN ABLE TO CORRECTLY DIAGNOSE OR CORRECT THE PROBLEM. THE FUMES ONLY OCCUR WHEN THE TANK IS FILLED JUST PAST THE 1/2 FULL MARK. I HAVE BEEN TOLD BY THE MECHANICS THAT THE TANKS WOULD NEED TO BE DROPPED TO FIND THE PROBLEM THIS WOULD BE AT A MINIMUM COST OF 1600.00$. NEEDLESS TO SAY I HAVE BEEN DRIVING MY VEHICLE 1/2 FULL FOR OVER 2YEARS NOW. OF COURSE I FEEL MY VEHICLE MAY STILL BE POTENTIALLY DANGEROUS, NOT ONLY THE EXPOSURE TO THE FUMES BUT ALSO THE RISK OF A FIRE OR EXPLOSION AND I FEEL THAT THE MANUFACTURER IS BEING NEGLIGENT BY NOT ADMITTING THERE IS A PROBLEM WITH THEIR DESIGN FLAW. FROM WHAT I UNDERSTAND IN THE CORVETTE FORUM THE DESIGN HAS BEEN CHANGED IN NEWER MODELS.