There's a difference in confidence with a higher vehicle that can't be matched with simply raising your seat in a lower one - whether that it is perceived or real confidence, there's certainly a difference. Are you shorter than average? I can only see this working if you're a short person, as I need my seat on the lowest setting the car will allow.
But don't forget we're in the OCUK Motors forum echo-chamber so be sure to make negative comments against SUV's, diesels, TT arches, PCP finance, and black alloys at least once per week.
Not sure how much is perceived but I certainly prefer a more commanding position for driving but personally I don't get a conference boost getting into a bigger vehicle but do feel less confident when I get down into a vehicle on the road but for some reason doesn't bother me on a track.