The R1T description says the lowest battery size is 105 kWh with a range of 230 miles. This would give a “miles per kilowatt-hour” of 2.19 miles / kWh. Using the national average electricity price of $0.170 per kWh, the cost per mile is ($0.170/kWh) / (2.19 miles/kWh) = $0.0776/mile.
Using a Honda Ridgeline for gas equivalence, it has a combined 22 miles per gallon rating. With a national gasoline price average of $3.803 per gallon, the cost per mile is ($3.803/gallon) / (22 miles/gallon) = $0.172/mile.
So by these calculations the electric option is a little less than half the price of a gasoline equivalent. Perhaps charging the R1T in public with a premium, such as with superchargers, the cost per kWh may go up, but that’s a disingenuous comparison so I agree with you that the article is making some big assumptions.
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