Details on electric car emmissions & efficiency
As the previous poster noted, there are a lot of advantages to doing the dirty part of power generation in a few well regulated places. The point of the 40 mile charge is that batteries are costly and their weight reduces efficiency. In the USA, most people, most days, drive less than 40 miles, so that's good enough to do without gasoline most of the time.
Here is a web link with specific details for the Tesla (data wasn't available yet for the Volt). To summarize, even with a coal-fired electric plant, and counting transmission line losses, the Tesla should result in twice the efficiency of a Prius and about the same emissions. For electricity generated from natural gas, it would have about half the emissions.
http://www.salon.com/env/ask_pablo/2008/08/25/electric_cars/index.html
The real payback comes if you run your electric car off hydro, wind or solar power. Then the emissions would be essentially zero. Standard cars don't allow these options...
Biting the hand that feeds IT
