THE VEHICLE IS EQUIPPED WITH "BRAKE ASSIST SYSTEM" WHICH IS SUPPOSED TO HELP TO ENGAGE THE BRAKE PEDAL FASTER WHEN THE BRAKES ARE APPLIED DURING A PANICK STOP. DURING A PANIC STOP, IN MY CASE AT 10 MPH, WHEN I HIT THE BREAKS, THE BRAKE PEDAL FELT HARD AS A ROCK AND REFUSED TO TRAVEL DOWN, EXHIBITING THE SO CALLED "HYDRAULIC RESISTANCE" WITH THE THE VEHICLE CONTINUING TO MOVE AND COLLIDING WITH THE VEHICLE IN THE FRONT. I TOOK MY E320 TO AN AUTHORIZED LOCAL MBZ DEALER, AUTOBAHN MOTORS IN BELMONT-CA, WITHIN TWO HOURS OF THE ACCIDENT FOR A CHECK OF THE BRAKES. THE DEALER REPORTED THE BRAKES OPERATE NORMALLY AND NO PROBLEMS WERE DETECTED ON THEM. THE PROBLEM IS THAT WE ALSO OWN A 1999 MBZ ML 320, AN SUV, WHICH BRAKES AND STOPS FLAWLESSLY WITH NO SIGN OF HARDENING IN THE BRAKE PEDAL. IF ANYTHING OUR 2000 E320 MUST HAVE BETTER BRAKES AND NO SIGN OF RESISTANCE, YET IT DOES NOT. IT SHOULD BE NOTED THAT WHEN THE BRAKES ON THE 2000 E320 ARE APPLIED NORMALLY, THEY OPERATE FLAWLESSLY WITH EXCELLENT GRIP, YET IN PANICK STOP THE BRAKES FAIL TO OPERATE PROPERLY.