It seems inconsistent to me from my own experience. A road I drive on to and from our development doesn't limit speed in TACC in either direction but if I go into FSD, it limits me to my set +5 mph in one direction and drops it to the exact limit the other. That usually results in me using FSD occasionally on the way home but when leaving on the same road, I only use TACC for that reason. I've tried it on the last 5 or maybe more updates including before and after HW 3 with no change.That would suck if fsd drives at speed limit.