are you REALLY sure you want that?
how much fuel there is is a quick glance into the dash, and you can control precisely the radio volume without even looking.
'turn up the volume', 'turn down the volume a little bit', 'a bit more',...
and then a radio ad going 'get yourself a 3 pack of the new magic wipers...' and car wipers going off.
id hate conversational ui on my car.