Miles / kWh not making any sense to me.

I have a 2019 40kwh Leaf, and I drive in Seattle Washington. The way I check my range performance is to divide miles driven by battery percentage used.

For Example: I recently charged to 100% and immediately drove 137 miles, about 2/3 freeway at 60 mph and the rest around 45 mph on secondary roads. At the end of this trip the remaining battery registered 12%. So I figure 137 divided by 88 (percentage battery used) = 1.55. Or 155 miles of range had I driven the car all the way down to 0%.

Whenever I drive in temperate weather with no rain, and no need to use cabin heating or air conditioning I get 1.49 to 1.55 miles per 1 % of battery. In other words spot on Nissan’s claim of 150 miles from a 40 kWh battery.

But if I look at my Leaf’s Miles per kWH meter it typically shows 4.7 to 5.1 m/kWh for the same driving in temperate weather with no cabin heat/air conditioning. At the low end of 4.7, my Leaf would only be using 32 kWh of a full battery to produce 150 miles. At 5.1 kWh my car would only utilize 29.4 kWh. I would think a 40 kWh battery manages itself so that at least 35 kWh is dedicated to driving the car. If so that would produce 178.5 miles of range.

What gives??

Thanks for listening, Scott Newcombe