Tesla owners who charge at home are kept up to date on their app with the exact cost of energy delivered to their auto. Mine averages about $25/month. Gasoline at 25 mpg would translate to about $125/month. My power comes mostly from hydroelectric sources. Long term most power will not come from fossil fuels (other than natural gas).
I suspect you live in Texas or somewhere in coal country. For us with homes in Florida with solar panels, charging can be virtually free if all driving is local. For us with homes in Washington with solar panels, cost is very low because the majority of the electricity is coming from hydroelectric dams.