Delta between car battery use and charger numbers

Using an emporia level 2 charger via 240 plug not hard wired, 87 kwh Venture+. Been doing multiple day trips to Seattle,100 or so miles roundtrip. Car is consistently saying im consuming 3.7 kwh/m with 65-66% charge remaining which would imply around 30 kwh consumed per trip. However the emporia charger is consistently recotding 34-35 kwh/ consumed. Called emporia and they tell me the error is in the car electronics not excess consumption by the charger. Concerned in regards to the long term cost and the implications of range by this +10% discrepancy. Comments? Experience?