I was looking for something else and came across this page: AVTA: Toyota Prius Gen III HEV 2010 Testing Results | Department of Energy The "Office of Energy Efficiency & Renewable Energy" studies cars in fleet usage and this page has the results. I recommend these two: http://www.energy.gov/sites/prod/files/2014/02/f8/0462_toyota_prius_ft.pdf http://www.energy.gov/sites/prod/files/2014/02/f8/6063_toyota_prius_ft.pdf Bob Wilson