As they say in the commercials, "Your mileage may vary."
However:
http://wheels.blogs.nytimes.com/2007...care/#more-278
see the third paragraph. . .
Apparently, 100 mpg is easy; the new line is 200 mpg.
Then there's the (experimental) car that gets over 2843 mpg.
http://www.msnbc.msn.com/id/24111771/