2013 Nissan LeafEnlarge Photo
At the cleanest end of the scale, manufacturing emissions play a huge part in just how clean a vehicle is.
Shrink That Footprint has used a 70 g/km figure, from which the 218 mpg figure is extrapolated. If manufacturing emissions dropped by just 20 g/km, the MPG equivalent would shoot up to 652. Raised by 20 g/km, it would fall to 131 mpg.
The same drop or increase in India, with its already-dirty energy mix, would see rises and falls of only 1 mpg for the same 20 g/km manufacturing difference. In the U.S, it's a 4-6 mpg difference.
There are several things to take from the data.
The first is that the impact of running an electric car depends hugely on where you're running it, and where the electricity is coming from. It's worth remembering at this point that those electric vehicle owners generating their energy from solar will be sitting nicely alongside Paraguay and Iceland in terms of low emissions--so from a green standpoint, it's worth doing.
Next: Manufacturing does play a large part in a car's emissions, but the significance of this varies depending on how clean the car is in the first place. Manufacturing is 100 percent of a car's total emissions in a place like Paraguay, but only a fraction in India.
The lesson there is that a smaller, lighter, less resource-intensive car will already have had a smaller impact on the environment before it reached you. Combine that with electricity--the sub-900 lb, hand-built Renault Twizy, for example--and the car's overall impact is incredibly low.
Additionally, electric cars are clean in other ways, not just CO2. With no tailpipe emissions, there are none of the nasty pollutants you get from any car with an internal combustion engine.
For standing right next to, the electric car will always be greener.
Finally, electric cars will continually get cleaner as the local grid improves. Cleaning up the grid is the quickest way of making electric vehicles cleaner--not to mention making your TV, oven and every other electrical appliance cleaner, too.