I mostly agree but vehicles shields you from the environment which is nice too. I don't know how many people function this way but being in my own physical bubble makes my brain expand.
Unbelievable, and you get downvoted for this. Folks, you've all had ideas come to you in the shower, yes? The heat, the warmth, the isolation from all else tends to make it a great place to just relax and think.
Now imagine a mobile climate-controlled bubble with no noise but whatever you put on the radio or barring that, the constant background of rubber rolling across asphalt, and you get that same effect.
All in all there are different environment which helps thinking. Long walks put your body in long term effort, releases endorphins which helps inspiration, or at least relaxation. Isolation helps too, be it showers, cars, toilets ... whatever works.
