I travel for business and while Lyft is a growing part of my travel plans, I still frequently rent cars. And I carry a cigarette adapter and mini-phono cable to connect to the car speakers. Yep, Bluetooth and USB connections are something to avoid.
I’ve done this for years, both because pairing can be problematic, but more importantly because un-pairing and wiping the infotainment system is often beyond my knowledge and/or time available when I return it. Privacy international just wrote a report on the situation – it’s worth a quick read: https://privacyinternational.org/sites/default/files/cars_briefing.pdf. Connecting to a car – either via Bluetooth or USB may be convenient, but you’re leaving a lot of digital breadcrumbs (and a few loaves) behind.
None of this is a surprise, and keep in mind that GDPR doesn’t protect us here in the US. It’s never a good idea to connect your phone to a strange device with a USB port or Bluetooth connection. Apple’s taken steps in recent iOS versions to give you more control over what information is transmitted, but it’s not perfect. For example, if you have the app for your own car on the phone, then rent a car from the same manufacturer, the app already has all the permissions needed to share your data.
So the net is that dumb connections are the only safe option when connecting your phone to a strange car. That means separate power (http://www.belkin.com/us/p/P-F7U013/ for example) and a mini-phono patch cable. The latter means that if you have an iPhone, you’ll need a Y dongle to get power and audio at the same time. Unfortunately, more and more models no longer have an audio jack, and only offer USB connections, so that won’t work. At that point I pull out my Bluetooth speaker and connect to it instead. The rental car privacy/security use case is one neither the phone or car manufacturers handle well at all.