It's easy to understand that, if you power your vehicle with electricity, you don't need to use as much gasoline. But, how much do you actually save, in terms of fuel costs and greenhouse gas emissions if you plug in instead of gas up?

A new report, released today by the Union of Concerned Scientists, called "State of Charge: Electric Vehicles' Global Warming Emissions and Fuel-Cost Savings across the United States," gives us a set of answers. In short, UCS looked at emissions and costs for both EVs and gas-powered vehicles and did a well-to-wheel (drilling, refining, burning for gas and mining coal, making electricity for EVs) "apples to apples" comparison and found that drivers across the U.S. would come out ahead with a plug-in car, some more than others.

The map above shows the three general categories that the UCS put different U.S. electricity grids into: good (dark blue), better (blue) and best (light blue). You can get the detailed explanation in the report yourself from this website or just grab the full PDF, but you can see in the map that the places where EVs and charging infrastructure are being rolled match up fairly well with UCS' "best" areas. But we also see that places like Colorado and Maine, among others, have an electric grid that is ready for EV expansion. UCS used the latest EPA data available, which was from 2007, so any states that have improved their electricity production methods since then.

Don Anair, the senior engineer of the UCS' Clean Vehicles Program, authored the report and said during a conference call announcing the report that, "For people who might have had doubts about the climate benefits of these vehicles, this report shows that they're positive, no matter where you live."

Running costs, too, are lower with EVs, even though Anair did acknowledge the higher up-front cost to buy a plug-in car. To truly maximize the money savings, EV owners in some cities, would need to change their rate plans away from the standard model into a plan that is designed for EVs, like a "nighttime charging" plan. The reports says:

Wherever EV owners "charge up," they can save $750 to $1,200 a year compared with operating an average new compact gasoline vehicle (27 mpg) fueled with gasoline at $3.50 per gallon. At that gasoline price, driving the average gasoline vehicle costs more than $18,000 to refuel over the vehicle's lifetime, but the owner of an EV can expect to pay thousands of dollars less to power his or her vehicle.

via AutoblogGreen