I have been able to explore this a bit, though I still have not found a list. The voice commands are extremely limited. It's missing basics on Garmin, and my 2005 (7 years ago!) Toyota Prius, including:
* Retail Stores: Can't tell it to find the nearest Costco, for example
* Temperature: Can't tell it to set the A/C at 74 degrees (this has been in the Prius forever)
Too bad! Overall, it's still better than 2011.