the problem with head room has to do with the length of your torso. that's why some guys that are 6'4" fit fine with a helmet, whereas i have a 1 finger gap between my head and the headliner at 6'2" with no helmet on (which means i'm screwed if i want to go to the track).
the z sits relatively low compared to most modern cars but i still consider it a high chair. my '92 acura integra's stock seat height sits just a few inches off the floor. my legs were practically straight. when i sat in my friend's nsx, that car was the definition of low seating to me. i felt like i was on the floor and it was great. there was actually more headroom than in the z. It also has what looks to be a bigger cabin space since its dash doesn't protrude out nearly as much as it does in the z. i find this incredible considering how small the nsx is compared to the size of our modern cars that are basically big, fat heavy cows. this picture should justify what i'm saying:
keep in mind that 350z next to it is lowered.
i think the only modern car that actually sits low, aside from supercars, is the lotus