[ghaff]

>You can easily search how far away is that storm?

Pull up radar on Weather Underground (and/or look at the hourly forecast) and you should have a pretty good idea.

Whether or not that's the best example, the point is that there are a bunch of things I might want to know/do while driving that I can't look up without pulling off the road someplace. And even if I could theoretically look them up by voice, it would probably be an exercise in frustration to try to do so.