For an ICE car, miles per gallon is very variable. An "average" may not be of much use, but for arguments sake, let's say it is 20 mpg. Add into this the cost of a gallon of gas. Again, it can vary from $2.40/gal. (our current cost) to > $3.00/gal. This puts a double whammy on calculating cost/mile.
Electricity costs vary widely per State/region, and, sometimes, even with time of day (although not here in my corner of WV where all day it is 11 ¢/kWh). For comparison, I am estimating ICE costs to be $0.20/mile ($2.40/gal. / 20mpg), and EV costs to be $0.03/mile (12 ¢/kWh / 4 mi/kWh).
My point is that for 95% of our driving we beat the pants off an ICEV. For that longer trip, which requires DCFC to accomplish efficiently (or sometimes, even at all), should we not be OK to pay "gasoline" prices for our electricity? Admittedly, 31¢/mile is a little above my "happy point". But anywhere near 25¢/mile is OK by me. Heck, we could even pay >50¢/mile and still have less overall annual cost to drive!