The National Highway Traffic Safety Administration said it is concerned that only about half of nearly 10 million vehicles have been returned for the repair. DO YOU ON THESE CARS? -- 1993-2004 Ford F-150 --1993-1999 F-250 (gasoline engine) -- 1993-1996 Ford Bronco -- 1994-1996 Ford Econoline -- 1997-2002 Ford Expedition -- 1998-2002 Lincoln Navigator -- 1998-2002 Ford Ranger -- 1992-1998 Ford Crown Victoria, Mercury Grand Marquis, Lincoln Town Car -- 1993-1998 Lincoln Mark VIII -- 1993-1995 Ford Taurus SHO with automatic transmission -- 1994 Mercury Capri -- 1998-2001 Ford Explorer and Mercury Mountaineer -- 2001-2002 Ford Explorer Sport and Explorer Sport Trac -- 1992-1993 and 1997-2003 Ford E-150-350 gasoline or natural gas vehicles -- 2002 Ford E-550 gasoline engine vehicles -- 1996-2003 Ford E-450 gasoline or natural gas vehicles -- 1994-2002 Ford F-250 through F-550 Super Duty trucks (gasoline engine) -- 2000-2002 Ford Excursion (gasoline engine) -- 2003 Ford F-250-F-550 Super Duty, Ford Excursion -- 1995-2002 Ford F-53 motor home chassis -- 2002-2003 Lincoln Blackwood