Does the average speed displayed by the PiP include the times when you are stopped at a stop sign or stop light (going 0mph)? It seems like it would be more useful for those of us concerned with EV efficiency to have the 'average speed' only from the times when the car is actually moving. For example, if you are almost always driving at 30mph but you encounter 'long lights' you would want the time spent waiting for the light to turn green to not average into your average speed. With the stop time included, it could appear that you drove much slower than what the electric motor truly experienced. You might be inclined to think that you need to drive slower than you did to get the efficiency you achieved.
Average speed is miles driven per hour and is calculated the entire time the Ready light is on. This is true for any vehicle that calculates mph. What you are asking for is a custom calculation based on your interpretation.
Well then, we certainly must be careful when making inferences about EV efficiency, not assuming the car's average speed indicates the speed the motor was operating at.