I ran in ev mode going 53mph

oops. Never mind. Didn't read the whole thread before responding.

I *do* know what real/pure/full-bore EV mode is, however. I just don't expect to get much of it in a Prius!

 

It turns out that the pulse-n-gliders were actually drawing up
to 5 amps out of the battery to help push the car along -- just
a little bit, but a little more motive power than just popping
into "N" and truly coasting. So it appears that drawing a *little*
bit out of the battery to help keep going isn't a bad thing, as
long as you don't drain it all the way down to 2 bars on glides.
Unless you're about to go down a huge hill, then that's a different
situation. The marathoners were on flat or very gently-rolling
terrain, which is sort of optimal.
.
_H*