After waiting nearly 8 months, I finally got my Echo Auto invitation two days ago. It was delivered yesterday and here are my initial impressions.
Well, it's really nothing special. It's basically the same as any other Echo device, except it's in your car.
The one significant thing about the Echo Auto is it uses Bluetooth for its data connection rather than WiFi. It does not support WiFi at all. When you first set it up through the Alexa app, it will connect to your phone's Bluetooth. Then you have an option to use Bluetooth for the Echo Auto's audio output or connect a 3.5mm audio cord to your car's AUX port.
The Echo Auto gets its power from a micro USB connection. Amazon included a USB cord as well as a 3.5mm audio cord and a plug with two USB ports for the car's 12v accessory socket. You only need to use one USB port for the Echo Auto. The other one is open to whatever you want to use it for, maybe your phone's charger cord.
It appears that the Echo Auto's main hardware is the 8-microphone array, a Bluetooth chip, and probably not much else. All of the heavy lifting is done on your phone via the Alexa app. All Alexa responses are sent via Bluetooth to your car's stereo or if you are using the AUX audio cord, sent to the Echo Auto which outputs through the 3.5mm AUX audio cord.
I suppose an Echo Dot can do everything an Echo Auto can do since it does have Bluetooth and a 3.5mm audio port. But that's only IF (a very big IF) Amazon enables the Dot to use Bluetooth for its data connection.
One benefit to using the Echo Auto is the size. It's pretty slim and doesn't attract unnecessary attention. It's smaller than a deck of cards. I'd say it's probably about 3/4 the size of a standard deck of cards. It comes with a nice rubberized mount. It also turns on quickly. I assume that's because the Alexa app is the one that does all the work. The Echo Auto is treated like a Bluetooth audio device on the phone. So it doesn't take long to turn on or to connect.
The data it uses will be from your cell phone's data plan. Keep that in mind since many cell phone plans have a monthly allotment of data that if you go over, it could be very costly. I don't worry about that since my plan is "unlimited" until I reach a certain GB and then the speed is throttled (lowered) until my next month.
Is it worth $24.99 (invitational price)? Yea, I think so. If you're immersed in Alexa inside your house like I am (I have 8 Echo devices) then you'll definitely appreciate being able to use Alexa while in the car. Is it worth $49.99 (regular price)? Yes, I would buy it for $49.99. It's something nice to have and it won't break the bank to buy it.