6'3" here, forget about anyone sitting behind me. The seat pretty much touches the back seat, although there is plenty of room on the passenger side. I took 2 people on a ride, guy who rode in the passenger seat was 6'1" or so and had plenty of room to move the seat up, and the person in the back just kinda stretched sideways and managed to squeeze in

We all know we didn't buy this car for the back seat, so who's complaining

 

The leg room is acceptable for normal people. When I tried an 05 Mustang out it was me (5'11" 172lbs) , a friend Becci (5'2" 120lbs?) and the salesman (6' 180lb?). The roof is low, my head was hitting the back window, so I had to slouch down a bit. It's OK for around town not for cross country ;-)

The convertible will probably have more head room. My 90 Mustang convert. was OK in that regard.

 

I don't care about room in the back seat since I never have to sit back there