^This is where the cabover sucks

. To made the totally flat floor, you need to lift the cab very high (
Scania S), otherwise you will have a small step between the seats (
Scania R) or even the tunnel higher than those seats (
Scania P or classis US cabovers).
So... if compare the
XF and
XD side-by-side...

Why? Why the young brother is more expensive?

Engine is smaller, tanks are smaller, cab is (a little) smaller... It definitely must be a mistake.