One problem related to brake master cylinder has been reported for the 2000 Subaru Outback. The most recently reported issues are listed below.
I own a 2000 Subaru Outback wagon. While driving approximately 20mph I attempted to make a routine stop in traffic. The car would not slow down, so I depressed the brake to the floor. The antilock brakes seemed to engage (I could feel the stuttering) but the car did not slow quickly enough at all. Notably the temperature was about 8degrees fahrenheit without windchill. I have since discovered that Subaru has recalled older (1999) and later (2002) models for this exact situation (hydrolic master cylinder brake failure at low temperatures). I plan to contact Subaru to find out what their position is on this. I do not feel the consumer should be held responsible for a known design flaw.