Consider the technology we are increasingly taking as a normal part of our lives. Mobile phones, tablets, sat navs to name but a few. And when we go driving, how many of them come with us? Whilst it would be highly inadvisable, certainly illegal, to fiddle around with a tablet whilst driving, mobile phones are not quite the same. Of course we should not make or receive phone calls unless on hands free, and smart phones (and smart cars) are increasingly being paired by the manufacturers of both.
A sat nav that comes with the car is fine, it doesn't involve having another device untidily plugged in to it, but some prefer the sophistication that Google Maps bring to navigation, with traffic alerts and warnings about speed cameras etc. Then they have to be plugged in. Even if not using the phone for navigation, it is convenient to give it a boost by plugging in to the car.
These gadgets have a draining effect on the battery of the car, and this is more noticeable in winter months. The number of battery failures caused by using them to charge hand held devices increases. This is not a warning to sy don't do it, just a tip to be careful.