I'm not sure, to be really useful in general case it would have to understand a good number of languages (what if you rent a car on vacation abroad and find tha

I'm not sure, to be really useful in general case it would have to understand a good number of languages (what if you rent a car on vacation abroad and find that you can't control anything unless you learn the local language?), work in noisy conditions, understand accents, and apart from navigation entry (although that usually serves as an exercises in zen and meditation, as you're trying not to put your fist through the dashboard as it tries to navigate you anywhere except where you actually want to go) it is much faster to turn the knob than expressing what you need in spoken word... Makes for a nice marketing video though.