State of Minnesota
According to the Great Plains Institute's (GPI) recent analysis, electric cars could provide large GHG reductions in Minnesota.
GPI estimates (using Argonne National Laboratory’s GREET Lifecycle Model), that EVs reduce GHG by "at least 61% in most cases (Xcel Energy electric mix) and 95% in many cases (for vehicle charging on renewable energy subscription programs)".
"Gasoline vehicles in Minnesota emit an average of 465 grams of GHGs per mile (g/mile) when accounting for the full fuel lifecycle, which includes energy used for fuel extraction and refining. In comparison, full lifecycle accounting of an electric vehicle (EV) in Minnesota results in only 183 g/mile of GHGs on Xcel Energy's 2015 fuel mix. It is interesting to note that because EVs have no tailpipe emissions, all emissions take place upstream, aka at the power plant and during vehicle manufacturing. And although it currently takes more energy to manufacture an electric vehicle and its battery than to build a gasoline automobile, as you can see in the above graph, the emissions from combusting gasoline vastly outweigh those from vehicle manufacturing."
The largest benefits will of course be achieved when EVs are 100% powered via renewable energy. In these scenarios, GHGs emissions from electric vehicles, would average about ~21 g/mile (or 95% less than gasoline vehicle).
source: Great Plains Institute