Well, just because I feel obliged to be a little subjective, yes, I think the new Stig drives a touch better, albeit I've only seen 3 of his lap runs on the show.
Of course, that could have been because his tires stuck just a little better, or the wind was blowing in just the right direction in some turns, or the track was warm, or some fat bastard on the other side of the world rolled to the right instead of the left somewhere in Indonesia...it's just hard to tell