It’s a little more complicated than that
Nothing, and I mean it, nothing beats the speed of a userusing hotkeys. Except one thing, which doesn’t exist yet: a neurointerface capable of understanding thought commands.
Sure, CUI is good for something like a kiosk, or something you’ve never used before. And for older people, who find everything new as it’s almost impossible to catch up with tech through all ones’ life.
CUI is not good for a PERSONAL car. The car’s yours. RTFM, customize it for your needs, then use it. Don’t fucking talk to your car, drive it, or enjoy the ride (when google cars are finally there).
And, if you’re riding a self-driving car, or any smart car, you sould never Ever think about defogging a window: this should be automatic by design.