Today I was attacking my fourth and final run and I was making a hard right-hander which required hard breaking. At some point in the braking zone, the brake pedal became very firm, as though there was a block of wood behind the pedal, preventing me from pushing it any closer to the floor. But the brakes weren't working as hard as they should have been. I ended up pushing and scrubbing though the turn, eating up all sorts of time. It didn't feel like fade- I've felt that before, which feels more like the pedal just letting go, and going more or less to the floor. This was different. It is possible that it was fade, and that the pedal was already to the floor. But I don't think that was the case. This was definitely something that felt like the car wasn't doing what it was being asked to do. I didn't enjoy that feeling. For the rest of the run the car behaved normally. But the damage was done. No help on my final run. One fellow competitor suggested it was my fluid boiling. But it's just an autocross, so I have a hard time believing that. Admittedly I haven't changed my fluid since I got the car, and I have 13k miles on them. So I suppose that's possible. Another said it was probably "ice mode". I had never heard of that. I have seen a few people on this forum mention that their FiST went into ice mode on a run, but not much explanation for it. I did have my ESC fully off (not sport mode). And I will certainly be changing my fluid before NASA's OktoberFast track day at VIR in October. (And I have a fresh set of pads ready to put in if it's looking like the ones I'm running are not going to survive the whole weekend) Does "ice mode" exist in our car? If so, how do we avoid it? If not, what else might have caused this awful behavior?