I have driven 100's of miles with continuous "auto pilot" (cruise and lane keeping). With a constant speed by using cruise control portion of auto pilot my "watts/mile" hit the lowest on the trips. In my X with 22" tires, It hit low 310's and even at one point hit below 300, which if amazing in an X with 22's. Autopilot is merely lane keeping with TACC. I have found it drives better on Interstates in low to moderate traffic than I.
Not sure
@PandAmonium why you experienced a difference. But autopilot, is nothing more than "lane keeping". You may want to do the same trip again with TACC only, which would cause the X to drive differently than you may on a given route -- yielding different regen or a different speed profile.