One problem related to brake grinding noise has been reported for the 2012 Mazda CX9. The most recently reported issues are listed below.
The Mazda Cx9 that we purchased has a acceleration problem when we go to stop. . Mazda has never been able to solve the problem completely. . We have had 2 brake boosters replaced under warranty. We feel the car is unsafe to drive and Mazda has not addressed the problem. They tell us nothing is wrong with the car. It know also has transmission problems with squeaking and grinding noises coming from the car. This is a design flaw that has not been addressed.