I tried it out today, because I had never had the driver's seat at maximum height with the backrest upright.
I am just over 6 ft. tall and slim. I could still get in and out just fine, provided I didn't have the steering wheel in the lowest position; that could be a bit problematic. It worked best with the steering wheel in the highest position, as I also had a good view of the dashboard screen then.
With the seat pushed all the way back and the backrest upright, there was still enough room for my legs and also (just) enough headroom, but...
I would never want to drive like that! Little to no support for the thighs; I was sitting only on my (bony) buttocks! Next to that, a bit difficult to arrange the rearview mirror properly and even with the high windscreen of the Jazz, having to bend forward when you are the first car at a traffic light. I didn't encounter any other disadvantages in those 5 minutes...
So, seat quickly back to the lowest position, the backrest a few clicks back again, the whole seat one click forward, the steering wheel as low as possible and all the way towards me. And that way I can drive for hours on end again without back pain or a numb butt.
