Miles/Gallon to Watt-hours/mile 

MPG =256 Wh/mile

Pretty simple  1 mpg = 8.775 Wh/mile
1 Wh/mile = 0.11396 mpg*


To beat a Prius you have to get down tto 250 Wh per mile.
All the other measures are deceitful - $ per mile, MPGe, etc.

They actually make it hard to find the Wh per mile for the Leaf.
Or the Volt.

Can't imagine why.

        * Assumes 0.61 kg CO2/kWh (unleaded regular gas against utility electrons.)
        (IPCC because the DOE does not make it clear -
        and 8.572 kg of CO2/gal. of E10    (US EIA 2018)