"Ergonomics" isn't a word I would personally associate with car design. Cars these days are generally all designed to the same anthropometric data. Considerations beyond that tend to be entirely subjective.

Are you designing a car Tinkerbell, or merely seeking to carry out some comparative assessment of potential models?

Thank you Jay and KieranD brilliant help. Nope I'm not designing a car ron hunter, I am carrying out an ergonomic assessment for a person with back problems who is about use a constabulary vehicle. The process and pro-forma we have is a bit weak and I want to improve it.

Tinkerbell I had a hunch that 'rehab' might underly your question (and would have felt better able to reply earlier if you had indicated this). Vital to ensure both the the body measurements of the person are compatible with the dimensions of the car seat and interior roof space and that factors affecting visibility and reach are carefully trialled, if necessary making physical adjustments to the car through the Motability or similar scheme. I was commissioned by insurers to do a similar exercise for a medical doctor who suffered chronic back injury after 3 road accidents in 18 months, yet needed to use her car readily to travel between 3 surgeries. Besides the ergonomic adaptations (to her office as well as the car), gentle but regular exercise of the injured muscle areas was an important element of her vocational rehabilitation. (It felt great to heal a doctor!!!)