2015 i3 Hold SOC charge not what it seems?

[alohart]

.. I'm beginning to wonder if the speeds my car displays is actual speed.

The i3's speedometer displays a speed that is a bit lower than actual (reportedly, 2-3 mph lower). This is apparently common practice with most cars to prevent the situation in which a driver was driving faster than indicated which might result in a speeding ticket. New tires rotate more slowly for a given speed than worn tires, so setting the speedometer to read a bit low protects against it reading lower than actual speed on new tires.

 

[jadnashuanh]

German, and probably EU law, requires that the speedometer never reads lower than actual, IOW, it cannot indicate you're going say 55mph when you're actually going 57. To ensure that happens, vehicles originating from there have a built-in buffer. The odometer, though, seems to be accurate. My experience is that BMWs tend to be going 2mph slower than the speedometer readout. There could be a slight difference between the 19 and 20" wheels, but they would be really close, other than accounting for wear.