engine assisted heating

With winter coming, I expect new and old Volt owners to be experiencing the dreaded Engine Running Due To Temperature (ERDTT). I you are interested in disabling this on your Volt, one of our members has an air temperature replacement module that you may be interested in. See...

I have a 2013 with the engine assisted heating. I have two options: turning the assisted heat on when the outside is cold or very cold. Which one should I use to maximize efficiency in the Chicagoland area? Also, when the car is charged they say to keep it plugged in..is that necessary and is...