 The EPA also estimated the upstream CO2 emissions associated with the production and distribution of electricity required to charge the vehicle . Since electricity production in the United States varies significantly from region to region , the EPA considered three scenarios / ranges with the low end of the range corresponding to the California powerplant emissions factor , the middle of the range represented by the national average powerplant emissions factor , and the upper end of the range corresponding to the powerplant emissions factor for the Rockies . The following table shows the Volt tailpipe emission plus total upstream CO2 emissions for the three scenarios , compared with other four popular plug @-@ in hybrids and the average gasoline @-@ powered car : 
