With an electric car, the miles / KWH is the metric of how efficiently you are using the charge in the batteries
The Bolt has several nice features that let us know how our driving technique, climate settings,terrain, and outdoor temperature is effecting that efficiency . From that data it predicts the expected range remaining in the battery based on the last 5 miles driven.
With an Insight which had an EPA estimated 70 MPG we have seen people with an Lifetime MPG in the high 90's.
The Bolt EPA range is estimated at 238 miles on a full charge, people have reached as much as 350 miles.
Knowing that simply getting off the highway or slowing down, and turning off the AC can yield that big of a range boost could really help with range anxiety if you find your self 50 miles from the recharging station with only 40 miles remaining on the predicted range.
I have been averaging over 300 miles of range since I got the car, loving it so far