Look, this easy enough to do if you have LeafSpy. Note your starting Gid's value, reset the trip meter and reset the mi/KWH meter. Drive the car for a while and note the current Gid's value, mi. driven, and the Mi/KWH value. Subtract the current Gid's value from the starting value and multiply the result by the KWH constant per gid. That gives you the number of KWH used. Divide the miles driven by the number of KWH calculated to get mi/KWH. Compare that to the dash gauge.
When I do this, the value I get is consistently a couple of tenth's lower than the dash gauge. What I'm curious about is what other people are seeing.