For me there are two ways to get the cost per mile on my electric bill, example one includes like ETS example the base charge plus taxes. The base is a sunk cost that is there whether or not I have an electric car. Just two different ways to calculate the cost per mile, use whatever one makes you smile...

example #1, my power bill is $90.73 ÷ 916 kWh = $0.099/kWh

Divided by 89% = $0.111 for the charger to add 1kWh.

Divided by my trip gauge's 4.0mi/kWh = $0.0278/mi

example #2, my power usage is $66.59 ÷ 916 kWh = $0.0727/kWh

Divided by 89% = $0.082 for the charger to add 1kWh.

Divided by my trip gauge's 4.0mi/kWh = $0.0204/mi