This is an old topic but going going to chime in. I have 3 vehicles all with Automatic OBD. I ordered the last as soon as I signed the paperwork for my 2016 Cruze.
It will not save you money except for learning from the logs. I coast to red lights and have got 37mpg city.
What it does do is provide stats for each trip you make that include start/stop times, mpg, fuel cost and map. You can add all fuel fill ups. It is also Alexa enabled to ask fuel level and last parked location. It also connects to the phone app OBD Fusion that reads several sensors in real time.