I WAS DRIVING ON THE HIGHWAY A SAFE DISTANCE BEHIND A LINCOLN NAVIGATOR WHEN THEY FOR NO REASON SLAMMED ON THE BRAKES AND STOPPED. I ENDED UP REAR ENDING THE NAVIGATOR. THE REAR OF THE CAR WENT UP INTO THE AIR CAME DOWN AND SPUN AROUND THREE TIMES BEFORE COMING TO A STOP. MY WIFE WAS INJURED. SHE SUSTAINED A BROKEN RIB CUTS AND SCRAPES AND CHEST PAINS. NO AIRBAGS NEVER DEPLOYED IN THE CAR AT ALL.