Susuto

@apeweek:
When a claim is made that, "A typical EV gets 4 to 6 miles per kilowatt-hour, which is considerably cheaper than gas," I feel it’s necessary to do the math to determine whether or not it is correct.

Given 5 miles / kWh and the nominal vehicular 30 miles / gallon, the standard 124,000 BTU / gallon gasoline, and your basic conversions from mi->m, BTU->Wh, etc, we can figure this out:

5 mi / kWh = 8.046 m/Wh
30 mi / 124,000 BTU = 1.328 m/Wh

So, your claim is correct: electricity is more efficient in terms of distance per unit power than gasoline. Let’s see how well that holds up when we apply average costs.

At present, gasoline in the US costs $1.81/gallon (!!), and electricity costs 12.1¢/kWh. Converting these to similar units (¢/kWh), we get:
electricity: 12.1 ¢ / kWh
gasoline: 4.983 ¢ / kWh

So, it seems gasoline is cheaper per kWh - but wait, there’s more. We now use these new factors to convert our above calculations to cost per unit distance:
(12.1 ¢ / kWh) / (8.046 km/kWh) = 1.504 ¢ / km = 2.42 ¢ / mi
(4.983 ¢ / kWh) / (1.328 m/Wh) = 3.751 ¢ / km = 6.036 ¢ / mi

So, after considering two separate interpretations, it appears you’re correct: EV cost of power consumption is lower than gasoline vehicles by a factor of at least 2.

Lastly, let’s do the same calculation using the cost environment of Hawaii. Hawaii’s current price for gasoline is $2.633/gal, so converting… 7.245 ¢ / kWh. Their cost per unit kWh of electricity is 36.02¢
(36.02 ¢ / kWh) / (8.046 km / kWh) = 4.477 ¢ / km
(7.245 ¢ / kWh) / (1.328 km / kWh) = 5.456 ¢ / km

Is seems that EVs are still marginally cheaper than gasoline, even with a high spread in cost per unit energy. Of course, that’s what happens when your engine efficiency is below 20% (as is true for internal combustion engines). And, as always, EV’s give you the option of, as you said, further reducing costs by slapping on a solar panel, or other self generation via wind or wave.