Or, just a thought, as someone who occasionally uses an older model car for road trips, you have several easy solutions. First, use an adapter like Belkins, there will be many more, or when you are on a long road trip, for most people something that rarely occurs, all you have to do is charge up your phone occasionally, *you get to about 80% in about 20 minutes. Second, you sound intelligent so you can't be so dependent on the GPS that you need to have it on for every bit of highway driving over long distances. Finally, you are describing a problem that doesn't really exist for you. If you aren't trying to listen to music, then the iPhone volume is loud enough that you don't need to "hear it over the radio system." Indeed, you would be an ideal candidate for the iPhone 7, since it has a new stereo speaker system built in with twice the volume of the previous one. You see you can relax as despite what the trollers are trying to convince you of, you have multiple solutions.