Just installed the Amazon Echo Auto in my Model 3 (early release -- me lucky!, me special!).
So far, I think it's going to be a great addition to the Tesla infotainment system.
I used the provided vent mount attachment in the rear HVAC vent, behind the console. Apparently there's also a flat dash mount that is available, or will be, so it can be mounted in the front of the car, as intended. (probably any one of those sticky gel dash mounts would work, though). Mounting behind the driver (center console) may not be what Amazon intended, but it works just fine, as far as voice recognition goes (so far). Maintaining the minimalist look of the dash area is also a plus. For power, I plug it into the rear USB port. Do those ports stay powered when the vehicle is sleeping? For now, I unplug it when I exit the car. I'll need to look into that more.
Setup was simple. Pair the device to the Alexa app on your phone, then connect your phone to the Tesla via Bluetooth. After the first time setup, it will always sync up when you enter the car with your phone.
After that, you can ask Alexa to play music,audiobook,podcasts, the meaning of life, etc, just like a regular Echo. However, navigation requests are now an option, too. It gives turn by turn instructions and the map shows up on your phone. Now that I think of it, it would be great if Amazon would enable the nav share function on the Alexa app, so anything you ask Alexa to navigate to, would automatically appear on the Tesla screen.
Personally, however, I find Tesla's nav and voice recognition to be excellent already. I'd only use Alexa for an edge case, if Tesla nav doesn't do quite what I want.
It is a treat to listen to my Amazon music playlists and audio books in the car. I know many of these functions can be done with just your phone and Bluetooth, but this is a fun integration.
Looking forward to the next roadtrip, and asking Alexa to play road trip games. ;)
Anyway, just wanted to give an early "review" for those clamoring for more options, and ways to augment Tesla's already excellent system.