http://www.epa.gov/greenvehicles/about.htmel_vacho said:I've never said it was the cleanest, only that it is cleaner than most.
"The average overall emission score for model year 2000 and 2001 vehicles is about 3. This average is expected to increase in future model years as cleaner vehicles are introduced."
"This year, EPA's new stringent "Tier 2" emission standards for cars and trucks officially take effect. Stricter standards mean cleaner choices for car buyers - the average score for 2004 models is 6, compared with a score of 4 in 2003."
Insight 5spd has a score of 6 or 7, depending on where you are. So it is unfair to describe them as "actually pretty dirty" in terms of emissions, and a more accurate description would be "slightly less dirty than average." EDIT - is it "cleaner than most?" This depends on your interpretation of the EPA use of the word "average." If they mean the "median," then yes, the Insight is cleaner (in terms of tailpipe emissions) than most. If they mean the "mean," then you cannot say for certain without more information, but you could say "cleaner than average."
EPA characterizes cars with scores as 8 or higher as "the cleanest 2004 vehicles offered for sale." Insight CVT, Prius, Honda Civic Hybrid, and many other conventional cars are scored 9 or 10, and you can see them listed here:
Note that the only car to rank 10 outside of California or NLEV areas (New England) is the Honda Civic CNG.