Yes they do
Drive at night and have someone watch the red reflection off the road
I haven't fully tested at what threshold they come on, but if you fully lift your foot off the throttle they come on after a fraction of a second
Yea, I just found this forum post and a few others that indicate brake lights do come on dependent on regen setting and the amount of deceleration, just goes to show dealers really know their stuff... They almost lost a sale.