But, Bill, a Tesla that replaces an ICE vehicle reduces tailpipe emissions at the same time it adds smokestack gasses from coal/gas plants. 

You need to compare the volume of CO2 emissions per mile between ICE autos and electrics. 

It takes far less CO2 from coal/gas to power an electric vehicle per mile--as I remember--than the CO2 volume emitted to drive  a similarly sized ICE vehicle the same distance. 

You should look this up; you'd find it interesting.