The 06 is rated with lower mpg...higher curb weight bumped it to a new category, changing the test setup (dyno resistance).
The 06 is also PZEV- the HCH took a 1mpg hit between the PZEV and non-PZEV version.
http://www.greenhybrid.com/discuss/2...site.5733.html
http://www.greenhybrid.com/discuss/h...erns.5669.html
Real-world change will probably be almost nil.