The EPA is exploring the idea of requiring a "graded" fuel economy label for cars starting in 2012.
See the graded and ungraded versions here:
http://www.epa.gov/fueleconomy/label.htm
If you have any thoughts, you can leave comments at the bottom of the page.
We are happy to note that labels for gas engines include a "gallons per 100 miles" measure.
Read a full explanation behind the new label ideas here, including a description of the need for "gallons per 100 miles".