I've sold my s3 and purchased a 2001 a4 tdi as a diesel commuter and have been having problems with all the brakes (front and rear) dragging to the extent that they really slow the car down. It wasnt like that on the test drive but now its happened 3 times and luckily each time I've been very close to home so could get home ok. I had all 4 brakes smoking the first time it happened and this was after a few successive stops. It wasnt until I pulled up that I noticed the heat and smoke coming from all 4 corners of the car. It also heated the alloys up so they were very very hot to the touch. Now had it been just one brake, I would have put it down to either a hose collapsing or a sticking caliper, but the fact all four are dragging makes me think it could be the master cylinder. The servo also seems to be working as when i press the brake and then turn the engine on I can feel the pedal drop further. Does anyone have any advice, experience or thoughts on this? Thanks in advance!