All comes down to the individual vehicle.
Wheels, Tires, Shocks and seats make all the difference. I know some cars --- smooth --- and in the total opposite mine will be hard stiff and not for looooooog hauls like my Suburban (last year Lakeland Fl to Dallas TX 18hrs
)
Just the difference in the seats can be major, some of them confine you in one position only. On top you have the seat belts, if you wear them correctly you can't reach (if any) the radio.
Then there is the size of the driver...
...that goes on and on...