The UCS is preparing to release a report titled, “Electric Vehicles’ Global Warming Emissions and Fuel-Cost Savings Across the United States“. You can download the full report here.
They compare electric cars to gasoline-only and hybrid cars, and find that depending on where you live, electric cars (charged from the grid) generate the same amount of global warming gases as cars with MPG ranging from around 38 in Michigan to almost 80 in California. The difference depends on the source of fuel for the electricity that charges your EV. Looking at alternative sources of energy, they estimate the following MPG equivalents:
So if your local electricity is generated totally from burning coal, your electric car would generate the same amount of global-warming emissions as a gas-burning car that got about 30 MPG. They state clearly in the text that they are looking at well-to-wheels global warming impact, including extracting, refining and delivering gasoline. I assume the relatively high emissions for solar (500 MPG) includes the impact of manufacturing solar panels.
On the cost side, they conclude that electric cars are much cheaper to operate than gas or hybrid, saving the owner hundreds of dollars per year, and several thousands of dollars over the life of the car.
Our electricity here in SRP Arizona is slightly cheaper than 11 cents (averaged over a year), and gas is slightly higher than $3.50, so the savings would be a little better. But both prices are expected to rise over the next few years, and who knows which will rise faster.