Riding in Cars-

I know having a smooth driver works wonders- no fast stops or starts, no rough shifting or swerving.
Automatic { just smoother} vs manual shifting

Easily adjustable seats - slightly reclined
Padding for seat belt straps
Pillows or pads for arms/ neck

You can get a waiver for the seat belt law due to health reasons - if the belt pressure bothers too much or you need to lay down.

some members make a bed type set up in their vehicle