[close04]

I think there can be a balance between physical controls for actions that need to and will often be used while driving, and touch controls for stuff that you will most likely use when standing still.

Controlling the temperature or music volume will be done while driving so they should be actual buttons that your muscle memory will reach with no mental effort or distraction. Adjusting the suspension settings or typing in a GPS address can be done via a touchscreen since it's unlikely you'll do it on the move and touch offers a better experience for this.

[clairity]

yes, that's the best split--make frequently-used features and/or features used primarily while driving physical controls, while rarely-used features and/or features used while parked can be touch-based.

however, address input should be primarily by voice control rather than touch entry. changing destinations (for whatever reason) mid-drive on a navigation system is dangerous and somewhat common, and voice control is the best option for keeping your eyes on the road (absent a passenger who can do the touchscreen data entry).