Sorry to flood with comments but if you read any of my other posts you know this car has Issues. 2004 XC90 T6AWD. When I start the car, I have to wait about 20 seconds for it to kick down before putting into gear, or else the brake pedal is hard to depress and not very responsive. Meaning, backing out of my driveway, if I need to stop, I need to press HARD and even then it's kind of mushy.

If I wait for kickdown to 1rpm, no problem. Now, say I'm going up a hill or letting off full throttle and suddenly need to brake: same issue. The car DOES stop. It's just a sudden and short issue that then goes away if I try to press the pedal again. What IS this? From my googling, I have come up with possibly the brake booster but my husband says master cylinder. Anyone ever heard of this?

Bought the car for $8500, have had about $4k in repairs so far (most covered under warranty, but still!)

 

My experience has been similair but viewed differently. When I cold start the car the RPMs rev to about 2000. Seems to be some sort of warm up procedure. 2000 rpm also seems to be at a point where the turbo is producing boost. I usually wait the 5-10 seconds required for the idle to drop to the normal 750-1000 rpm. If I go right away when the car is on high idle it seems as the brakes are not doing their job as well however my observation is that this is due to the amount of power the engine is producing. At 2000 rpm the car wants to GO.

All of my cars do this and have since new. My Audi RS6 really does it, but given the horsepower it has I'm surprised I can hold it back at all.

Again, this sounds totally normal to me.