on hard application of the brakes on my used 2011 Sport, I get a loud groaning noise which sounds like it is coming from the front end. I looked at the brakes while the car is parked and noticed that the rotors seemed a little rusty all around and the driver side rear rotor was scored fairly deeply. I didn't get any feedback through the brake pedal so I suspect that since this was a fleet vehicle and has 75000 miles on it that the system may need flushing and the rotors turned. It stops strongly and this noise is noticeable in the last feet of the stop. The loudness is greatest with the severity of the stop. Any suggestions? Update,on Thursday the 11th, I took it back to Carmax and had them look it over. They `greased' the calipers' and turned or replaced the worst brake rotor(the scored one). The car didn't make any groaning noises on the way home using normal stopping pressure at lights and signs so maybe their work fixed the issue. I don't know if these brakes slide on pins or not but it seems like the prior owners didn't keep up with routine maintenance.