TBH, the most astonishing reveal from the study for me was that Hybrid owners weren’t charging their vehicles. Unfortunately, the why isn’t covered in the study since it seems to just be hard math and statistical analysis.
Are they just not plugging in at night?
Too frustrated with the battery draining too quickly?
Driving too far for the battery to meaningfully contribute between charges?
Is the extra hardware mass making the ICE that much less efficient?
Laziness from having to fill both the battery and the gas tank?