I never used Android Auto but found this idea interesting, although I see it's just a simple mirroring of phone's screen that seems to do less of a job than Google maps aspect does, imho. Although I am reading more and more places manufacturers of vehicles offering this quasi navigation option (i.e. navigate if you bring your phone ;) I am a heavy user of GPS ever since Garmin V was first available, and for any serious trip would always bring one with me. I used to schlep a huge Garmin 2610 everywhere and had it mounted on the motorcycle as well. That thing was so large, that somewhere in Montana at a gas station an older gentleman asked me if I was watching TV on my motorcycle. I love my Montana 600 on the bike as well as in cars, since it's very portable.
Recently, since I got a decent Android phone now, I use it allot in the old '02 Subaru WRX, which has none of the modern bluetooth accoutrements but has a great speaker system and a cassette and FM radio. The phone attaches to the windshield with a Garmin RAM suction cup, a short Ram arm and an X-grip holder. Since my eyesight isn't that great anymore using small screens without reading glasses, what I found very convenient is a bluetooth to FM radio transmitter that plugs in the cigarette lighter adapter and also provides recharging if needed.
With this I can listen to perfect quality and strong Spotify music or anything else for that matter, through the car's radio tuned to the FM station on the device above, while at the same time receiving voice directions from Google maps (it fades music when it needs to speak, and then restores music volume). The only thing I glance at the phone for is the number of miles or hundreds of feet before next turn, but that is announced as well over audio so I am all set. This also enables me to speak hands free and hear the conversation in the car's speakers. This "kit" is very portable so it can be used in any rental vehicle too.