Getting a better GPS signal
I'm always getting a poor GPS signal on my iPhone 6 and iPhone 6S Plus, as I drive for a living and use satnav apps a lot, including TomTom, Google Maps, WAZE it would improve my work life considerably if I could get a better signal. In my car I have a built in satnav but the updates are so expensive that I don't want to go down that route [excuse the pun]. What I'd prefer is a tried and tested enhancer to attach to the iPhone that gives a good signal and can also keep my phone charged. In the past when I had the iPhone 3G I used the TomTom adapter but I don't see them available for the later models. Help.
iPhone 6s Plus, iOS 9.1