Mode-based UIs on touch screens don't work well when you need to keep your eyes on the road. The reason traditional dashboards are so easy to use while driving is because each control is always in the same place and can be located and used without seeing it.

Most cars have a fixed set of dash controls: climate, audio, and possibly navigation. Climate controls can easily be just three dials and a couple of buttons (temperature, fan speed, vent direction, and AC/recirculate buttons). Audio can be 4-6 preset buttons and a volume knob, and maybe some little treble/bass/fade/balance knobs. Yet many vehicles completely screw this up.