Sorry to start another thread on this, but the search function doesn't seem to be working any more.
Anyway, 2 episodes this coming week. On Tuesday 21st, 8pm on BBC2 they're doing another US road trip. And on Boxing Day (again 8pm on BBC2) it's the Christmas special, featuring a Middle Eastern road trip.
Of course, iPlayer will have it too, and if you're desperate, no doubt Dave (the channel) will put them on loop in the new year.