I've spent some time playing with BringGo and my Moto G 1st Gen ($90 new unlocked on Amazon).
Day 1: Connect to my 2014 Spark EV via Bluetooth. The BringGo opening screen on the Moto G says "this device has not been tested and BringGo may not function" or something like that.
On my first attempt at using BringGo for navigation, it had frozen on my start point; the map did not track my movement. But after a disconnect and phone reboot, it hasn't happened again.
Day 2: Left the phone "on" in the car overnight, hidden away from sight, but plugged in to USB for power. Turn on the car, phone begins to charge, boot it up after a few minutes. Another 30 sec or so it activates its Bluetooth connection, and MyLink shows active icons for BringGo, Pandora, TuneIn. Tap the BringGo icon, and up it comes, connects instantly and quickly orients itself. Drove to work and BringGo follows my moves.
Day 3: Get ready to drive to work. It's only a 1.4 mi drive (to a shuttle stop, actually), so I don't have much time to fool with this. However, this time I turned off the phone last night before retiring, so this morning it took less time to boot the phone since the battery had partial charge. Same result as yesterday.
This is what I wanted in a navicomputer in the Spark EV. Pseudo "onboard", if you will; the in-dash display is good enough. I don't care about the phone's battery state as long as it has juice and/or a connection to power, so I can tuck it away where it is out of sight.
The connection seems solid. I bought the Moto G (new) for $90 on Amazon.com for the specific purpose of using it in the car for Nav + music playing. It has 16Gb of storage, so there's plenty of room for maps and tunes. No SD card slot. However, SD cards are so cheap these days, a 32 Gb microSD card for $18 on Amazon holds a ton of music. I bought one with a USB adapter and will try that if more music is required (for road trips!).
I'll test BringGo this month until a late Oct. Spark EV road trip from Atlanta - Charleston, S.C. Only two CCS charging stops (Athens and Augusta), so it will be slow going for part of the journey. I've already driven between three Georgia cities in one day (Atlanta - Gainesville - Athens - Atlanta), fast charging at each stop. The Spark EV doesn't even break a sweat.