Recently read that the Gen3 lost about 3 inches of flattish space over the Gen2, how does the Gen4 compare?
It's really hard to say: with the seats scrunched right forward, or? And: clarify "flattish"? I'd call all the generations close, around 6'.
Seats forward or back (with or without headrests). Here is the referenced linked : Camping in the Prius | Page 4 | PriusChat