Nice try. Power plants produce AC current, which has to be converted to DC to be stored. Power plants have to run at a level that exceeds demand, meaning, they can't just turn a knob and increase power output, all these vehicles plugged in will increase the demand to a point they will have to run at a greatly increased level, meaning more pollution expelled, if you really buy into CO2 being pollution.
Now, back to the process of charging the battery, that the 240V AC has to converted and stepped up to 400V DC which causes a loss of energy in the form of heat. So it takes more energy to charge the battery than the battery has to use to propel the vehicle down the road. Meanwhile, on the vehicle side of things, the PIM kicks on the coolant pump to keep the battery and OBCM cool. If the garage is warm, like during the summer months, the AC compressor(400V DC pump) kicks on to help the coolant heat exchanger lower the internal temp of the battery. The coolant fans are also kicked on to allow the AC system to function.
Yes, electric cars have a place in our society for those who can afford them or like to consider themselves tech savvy, but are impractical for a majority of us common folk.
So to summarize this, once the battery is charged, they can be very efficient. But remember that battery runs the radio, lights, instrument cluster, wipers, AC, etc. The high mile range most claim are under perfect conditions, moderate speeds with no peripherals working. And what do you do when you find yourself 40 miles from home and your range shows 20? I stop at a gas station.
