Modern cars a smaller inside, even if they are bigger from the outside, than classic ones from the 50ies to the 70ies, because it's so much plastic end electric stuff inside (airbags are needing much space).
BMW has started with these big dashboard-constructions in the 70ies, later the other have done the same.

No kidding, in my NSU 1200 C I had more space for the legs and to the side than in a modern 5 Series BMW.

Is there any modern passenger's car, where it's possible to slip from the driver's seat to the passenger's seat?
You see...