I can't comment on the tax thing, as I haven't researched it since before I got my HiHy last year.

Regarding rear-seat headroom. I am also 6'3", and I've had no problem fitting in the rear of the Highlander. I usually choose to drive, but on the few occasions I've sat back there, no problems. Yes, I have the moonroof.

Love the vehicle. Just went over 20K miles, and the *only* problem we've experienced has been a tab coming loose in the center console cupholder. Compared to the Touareg we "up"graded from, this troublefree performance is joyous at the very least. So it's strongly recommended from Moneypenny & Co.