Thanks for the link. I missed anything on changes in headroom though they showed head clearances to a dummy. Also a really interesting drawing showing height reductions as follows: (Edit: drawing in post above) Top of Hood 61mm Top of Car 20mm Bottom of Car 10mm Floor of passenger space 59mm Top of Spoiler 60mm Bottom of trunk 110mm From this drawing it looks like vertical space from floor at front seat is greater but space at back seat is unclear as are seat heights and how belt line matches up with seat heights.
So the the seat is 59mm lower and the car is 10mm lower. That makes the top of the seat 2.7 inches lower than in the 3rd Generation. That is going to a be problem for some people, especially older people like my parents who think this 3rd generation is too low.
One thing that maybe can be salvaged from the above measurements: they show front AND rear seat clearances. Assuming the rear is less: subtract it from front, then repeat on your car. Sit in front passenger seat, check your headroom. Then repeat in back seat, and again determine the difference. This'll at least show how much head room falls off in the rear, say third gen vs fourth, maybe.
We don't know the position of the front seat or the configuration of the dummy. Even if we assume that its measured fully down and fully back for the front seat measurement, that position was very different from Gen 2 to Gen 3 and could also be very different again for the Gen 4. Also, we don't know the slope of the front seat: I have a ton of clearance when the seat is laid right back.
I suggested to use the front passenger seat, which isn't height adjustable. But yeah, grasping at straws. The one bullet proof method: someone at one of these shows: sit in the back seat measure clearance, then repeat in a 3rd gen, not sunroof versions in both cases.
Possible I guess but most of the other arrows seem to point at the item that's changed. Also, if it was seat height, I'd expect to see separate arrows with different dimensions located near the persons butts in the front and rear seats.