Not sure where they came up with a 3.9l/100km number for electrics. Modern EVs such as the RAV4-EV and the Tesla are generally less than 1.75l/100km (175 wh/km) using a rough 'fuel' comparison between petro and electric at .1 liter of diesel ~ 1 kWh electricity. Although coal puts out somewhat more CO2 than diesel, it isn't twice the amount - perhaps 20% to 30% more than diesel.
But both fossil sources ignore the amount of pollution generated during extraction, transport, etc. as do many nuclear energy carbon calculations.
They also don't seem to account for the possibility that diesel vehicles can be powered by more carbon neutral sources such as waste vegetable oil or biodiesel, or that electricity can be generated by any number of sources that are cleaner than coal.
Nor do they account for the likelihood that lithium batteries will be recycled as opposed to going directly to a landfill.
The best possibility would be a vehicle that could use multiple types of fuel/power, so the driver could decide to use electric, or diesel, or natural gas, or whatever fuel happens to be best / cheapest / least polluting depending on how far they need to go, availability, carbon burden, etc.
In my situation, electricity is the best answer for my daily drive around town and to work. Fortunately, our power is relatively clean here in Alameda -
Alameda Municipal Power - Power Content Label
At 1.51l/100km (electric equivalent) for the past 90 days in the Citicar, and using Alameda's power content, 'fueling' it with electricity it is about as clean and as cheap as I can get in a car... Perhaps someday I'll install solar.