I did a search and didn't see anything on the topic. But I thought this was interesting article.
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One plug-in hybrid, a version of its Saturn Vue, would have an electric range similar to that of the Toyota car: about 10 miles. The other is an entirely new vehicle called the Volt, an electric car that would use power stored from the grid for the first 40 miles, then rely on electricity from an onboard gasoline-powered generator for another 600 miles.
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The part about the generator is an interesting idea. Heck putting a small generator in the car I could disconnect the alternator lol instead of the solar panals.
Here is the whole article....
http://www.technologyreview.com/blog/editors/17664/