How fast does the car end up going down a long 5% grade? You are limited by aero drag and the mechanicals in the car, since there is in actuality no real 'neutral' which allows you to disconnect the drivetrain and just coast . . . . and the car's Cd is just terrible at the speeds involved in such a long run down such a steep grade. No question you would get much different results in the Tesla . . . . you might be going 140 mph at the bottom of the hill!
It's easy to see where using (our) neutral down a long grade limited by aero and friction to whatever speed that gets you is less efficient than regenning and going down the long grade even just 3 or 4 mph slower will have you with a fuller battery at the bottom, no question
. . . . but, what have you proved??
That an iMiEV has a terrible Cd - We knew that
If this same test is done on lesser hills at 35 mph, you won't have those huge aero losses and that limiting of speed done while regenning might mean you have scrubbed off momentum recharging that you're going to have to pay (in electricity) to get back to either maintain whatever speed you want to maintain after the coast, or you pay more to make it up the next hill - I suspect the latter is true for sure. Then
, you have the energy conversion losses to add into the equation too which are probably more than the cars quiescent 1.2 amps that you were losing while coasting. So, you can't make a blanket statement about coasting down hills without factoring in the aero losses based on the speeds involved - It might be
more efficient to coast at 35 mph than it is to coast at 70 mph or more and regenning just enough
to reduce the aero loss just enough
is more efficient when aero is playing a big factor like it does at higher speeds, yet the calculations for half that speed would give you a completely different answer . . . . right? I'm pretty sure they would
I think if you're going to design an EV to win the Eco Challenge, you would want a real neutral, plus the ability to shut down all current draw in the car while coasting . . . . which just isn't safe to do in a real car driving on real roads among real traffic
Truckers love to tack on an extra 10 or 20 mph at the bottom of a hill to 'use' to make it up the next hill and they know that's more efficient than riding the brakes down the hill (where they get no energy return) and then burning extra fuel to make it up the next hill. Now you're trying to prove whether or not an EV which can return 80% or so of one of the
the speed limiting forces is better than just coasting while using the cars constant quiescent current . . . . or not . . . . and that's probably very speed dependent
IMCUO (In My Completely Uneducated Opinion) I think you guys set out to try to prove something one way or the other by carefully examining the 6 or 7 factors you thought
governed the situation, only to discover in the end that there are actually 9 or 10 factors to consider *and* those unexamined forces threw all your calculations out the window
But, I might be completely wrong!