I'm 6 feet tall and I don't know if anyone has ever ridden directly behind me. Part of that is due to the manual shift. It throws me off if I have to adjust my seat forward a lot. However, I do not have the seat all the way back. When I do, I find it impossible to push the clutch all the way down, so I assume a person several inches taller than myself could still drive my car. My worst problem is when I get too close to a stop light. I have to lean forward and peak up sometimes to see the lights.
I had a 6'2" guy ride in my backseat a couple of times. He was comfortable. Maybe not for a cross country trip, but it was fine for a ride across town. The hardest part for him was actually crawling into the back.