To help inform future discussion, I have done another test of my Prius' "EV" mode. Some values here are guesses (reasonable ones, I hope) or are "roughly" where I could not obtain readings.
- The car is a 2005 UK-spec "T4" model Prius, unmodified in ways liable to affect performance. (Eg, it has floor mats.) Seems to be in good condition. This model has "EV" (Electric Vehicle) mode. When engaged, by pressing a button, dashboard icon lights and car tries not to use petrol engine (limited by battery state and effort/speed being asked of car).
- Weather: 7C (44.6F), overcast + enough drizzle to warrant the wipers on "slow intermittent". Good visibility.
- Wind: Rain drops were falling at an angle to the vertical of
- The Course: A local road, more or less level but with gentle curves and local undulations (worst gradients 1:100). Reasonable surface but not truly "flat", except for last 100yards. Lack of other traffic allowed car to run without halting.
- Battery: At start, main battery showed 6/8 charge. I do not know whether this was "barely 6/8" or "almost 7/8". (Datum: main battery never seems to reach 8/8 -- display turns green where 7/8 might become 8/8.)
- The Method: I drove the car, from cold, some two miles to the Course. Pulled over and switched off all electrical loads except wipers. Reset trip meter (which measures in 1/10 mile). Pressed "EV" button: dashboard icon lit. Moved off gently and speeded up to 17-20mph, never exceeding displayed 20mph. After car had gone
- FWIW: within a further 6 miles of unstressed steady driving at
HTH.