Sudden acceleration in 2008 Matrix automatic: First known failure. Car brought new in September 2007; odometer: 6000 miles. While driving approximately 35 mph on even straight smooth roadway, there was a sudden acceleration to greater than 70 mph. When brakes were applied, they depressed to floor without any effect. Car continued to accelerate rapidly. Shifted to neutral without success. Car slowed after being placed in reverse. Coasted to a stop. Placed gear in 2 and drove slowly home - approximately 1/2 mile. Floor mats were not near either pedal and were kept stationary by hooks designed to keep mats from shifting. Called Toyota service department: Told that floor mats were the problem; talked to service managers who stated that the sequence of events described were impossible, no problems were known to exist for Matrix and greater than 99% of sudden acceleration problems were due to driver error. After a discussion, the car was evaluated by the service department. The following was reported: Floor mats held in proper place no objects on floor normal brake pedal operation normal accelerator pedal operation health check - powertrain, chassis, electrical, network systems - ok computer codes - no abnormalities found normal throttle body inspection tires with normal wear & function problem was not duplicated on test drive. Was told that the car is functioning normally in all areas and has no problems. Implied that my experience was a misperception or misrepresentation. Assessment: There was a significant malfunction in the Matrix which could have led to critical injuries or loss of life. Only due to the traffic flow at precisely that moment, no one was injured. The Toyota service departments denied that the problem exists. Recommendation: Sudden unexpected acceleration should be investigated until an answer /solution is found. The findings should be shared with the public. The cost for repairs should be paid by Toyota.

- Tampa, FL, USA