I haven't had deep sleep alert yet but did notice on my digital volt monitor plugged into cigarette style plug that what has been normally been voltage of 14 to 15 volts while driving was 13.1 v this morning for the full time I drove, about 25 minutes. Then in the afternoon drive back 15.1 volts...
I thought it meant combination ice and battery, I'm assuming three possibilities of power , ice, battery, mixture of both. Just my guess , no actually facts.
The 39.9 mpg was figured by hand, I found each h tank full was over estimated by about 2 mpg by computer, so probably subtract 2 mpg from the 52.9 to be closer to actual.