I think another factor has to do with the fact that the Camry has a larger, more powerful engine -- this will cause its peak efficiency spot to be a higher speed than the smaller 1.3 and 1.5 engines on other hybrids, which peak at around 50mph. While that may be lower than 65mph, if that is average 65mph driving with load and not steady 65mph, you may be dropping below the efficient range on some of the hill climbs.