2015 Audi A8 Brakes Problems

ON THREE SEPARATE OCCASIONS, THE VEHICLE DID NOT STOP WHEN THE BRAKE PEDAL WAS PUSHED AT HIGHWAY DRIVING SPEEDS. THIS DOES NOT HAPPEN ALL THE TIME. CAR HAS BEEN TOWED TO AUDI DEALERSHIP TWICE, YET THEY FIND NOTHING WRONG WITH THE VEHICLE BECAUSE THE DIAGNOSTIC TESTS THAT THEY ARE RUNNING RELY ON THE COMPUTER, WHICH IS DEFECTIVE TO BEGIN WITH AND NOT RECORDING THE NECESSARY FAILURE (CODES) FOR WHEN THE BRAKES FAIL ON THE VEHICLE. WE HAVE NO CHOICE BUT TO CONTINUE DRIVING THE PER AUDI DEALERSHIP (OPEN ROAD / AUDI MANHATTAN) UNTIL LEASE END.

WHEN BRAKING THE CAR VIBRATES, SOMETIMES SO VIOLENTLY THAT IT IS UNSAFE TO KEEP APPLYING THE BRAKES TO CONTROL THE SPEED OF THE VEHICLE. CURRENTLY THE VEHICLE HAS BEEN IN SERVICE SINCE JUNE 27, 2015 AND HAS BEEN DRIVEN 21,000 MILES. HOWEVER, THIS VIBRATION HAS BEEN NOTICED EARLY IN THE LIFE OF THE CAR. ORIGINALLY, I THOUGHT THE VIBRATION WAS DUE TO THE ROAD SURFACE OR CONDITION, BUT I HAVE COME TO REALIZE THAT THIS PROBLEM IS A VEHICLE FAULT. IN THE MOST RECENT INCIDENT WE WERE DRIVING FROM PAYSON, ARIZONA TO MESA, ARIZONA USING THE VEHICLE CRUISE CONTROL. ON THIS ROAD, US 87, THERE ARE A FEW INCLINES OF ABOUT 6% THAT RUN FOR 2 TO 3 MILES. AS THE CAR GAINED SPEED GOING DOWN THE INCLINE THE CRUISE CONTROL WOULD APPLY THE BRAKES AND EXTREME SHUDDERING AND VIBRATION OF THE VEHICLE OCCURRED. TO MAINTAIN A SAFE SPEED WE EVENTUALLY REVERTED TO ENGINE BRAKING TO CONTROL A SAFE SPEED. THIS HIGHWAY IS VERY WELL MAINTAINED AND I AM CERTAIN THAT THE ROAD CONDITIONS DID NOT CONTRIBUTE THE THE VIOLENT SHUDDERING OF THE VEHICLE. MY WIFE AND I HAVE BEEN RETIRED FOR SEVERAL YEARS AND WE HAVE NOT DRIVEN THIS VEHICLE HARD OR HAD ANY EMERGENCY STOPS. THE VIBRATION IS PRESENT, TO A LESSER DEGREE, AT SLOWER SPEEDS AND VARIES CONSIDERABLY DAY TO DAY. I HAVE OWNED TWO LEXUS' PRIOR TO THE A8L. BOTH THE LS400 AND LS430 WERE DRIVEN 120,000+ MILES WITHOUT A BRAKE PROBLEM OR VIBRATION DURING BRAKING. THE PADS MAY HAVE BEEN REPLACED ONCE, BUT THE ROTORS NEVER HAD A PROBLEM.