I drove my mother in her 2005 lexus es330 from orlando to jensen beach, fl for a weekend visit with her sister. the car was purchased in the summer of 2005. the car was driven locally and this was the first time it had been driven on a highway at high speeds. i drove the car on i-95 for 2 hours until i reached our exit. i pressed on the brakes to slow the car down and nothing happened. i continued braking and was getting alarmed that the car did not slow immediately. i maintained pressure on the brake and finally the car slowed before we reached the stop light at the end of the ramp. my mother,as a passenger, was not aware there was a problem. on the return trip while i was driving it happened again. after 2 hours of driving, i exited onto the local roads and braked as i approached a red light. the car did not slow down. i pressed hard on the brake pedal and the car in front had stopped. i screamed to my mother "the car is not stopping!" she screamed out that we were going to hit the car in front. i continued to press on the brakes and the front end made a loud mechanical sound like a metallic clunk and the car stopped. when i got to my mom's house i called the dealership and told them the brakes failed twice. they told me to have her bring it in for inspection. my mom was 87 at the time and i said she is not driving this vehicle anywhere. the dealership picked up the car and said they found nothing wrong with the brakes.the next week she got a phone call from toyota california to inquire into the incident. the company said the dealer found a lot of oil on the left wheel as if i had hit a pothole. my mother could not react as she had not been the one driving the car.i can tell you there was no pothole! i have driven it twice again on the highway using the same route. it never happened again but i never feel safe in that car. i think toyota knew something was wrong with the vehicle but did nothing. this car was not part of the recall but it should be examined again.