Do you have an automation app like Tasker or something like that? It just sounds weird... If you don't use Driving Mode at all, you could also disable it entirely (Settings/More/Application Manager, go to the "All" Tab and look for Driving Mode, click on it to go into the settings and select "Disable". This prevents the app from running at all and it even removes it from our app drawer. Should you want it back, you do the same but the app will show up at the very bottom of the All tab).
This was my problem .. I didn't know what I was doing when I selected WIFI for "car" ... I have a 2007 Audi a3, and it DOESN"T have WIFI ... so my bad ... I said "NONE" in the CAR location setting (settings - more - location services, my places - car - NONE) and the issue is resolved.