well let's see, you certainly didn't help the hch.ii database with your mileage!

seriously, there are hypermilers in both databases. there are lead footed drivers in both databases and there are lots of "normal" drivers in both databases. given the sample sizes, the drivers in both databases have been averaged out. i don't see the drivers as the reason for the hch.ii as having great mpg. as i see it, the only factors at this point that could be affecting the data are (and these all affect the hch.ii data in a positive way):

1. summer/winter fuel. the hch.ii is just starting to benefit from the summer fuel while the prius gen ii has at least a year or more of this benefit already built in. expect the mpg in the hch.ii database to go up b/c of this.

2. break-in time. the hch.ii data may improve somewhat at the cars in the sample break in. the prius already has this data built in for most of the cars in the sample. there is no definitive data that shows that break-in actually affects mpg. so, i think this is almost a moot point.

3. driver learning curve - the hch.ii data may improve somewhat as drivers learn how to driver their hybrids. again, prius already has this built in for most of the cars in the sample. more than break-in, in think this factor can and will have a significant impact on the data in the hch.ii sample. i'm still learning how to maximize my mpg and i've owned my hybrid for 4 months.

4. early adopters - here the hch.ii may have more early adopters in its sample than the prius. of course this is less and less true as months go by. however, we don't know anything about how early adopters relate to mpg. and, in the end the sample is large enough and enough time has gone by that any effects of early adopters is pretty minimal.

my conclusion is that the data has not yet stabilized for the hch.ii. that we will see an increase in the mpg for the hch.ii but that this increase is not due to a different driver set but rather to other external factors.

i'd be interested in hearing others' comments/analysis on the data.

cheers,
neil