Loved reading this . I've had many of the same experiences.I've noticed if you keep your foot on the pedal just right you can spike it to 100. I suppose this is the I2's elusive "EV mode." I noticed someone mention it on here and tried it for myself, it's do-able. It's not sustainable for too long because of so many factors encountered on the road.
I was cruising along with the MPG gauge pegged at 100 driving 55MPH for a short time yesterday until I drove across a bumpy bridge which screwed it for me, you're a hair-trigger of pedal pressure from losing it.
It seems easiest to get into when you're coming down from the other side of an incline, and I do not mean completely remove your foot from the gas pedal.
One of the things I've noticed, in doing this alot, is that the battery will run down. Then to recharge the battery, I'll drive through a period of a notch or two of "Chg", and reduced mpg on the slider. Sometimes I wonder if the mpg decrease from recharging the battery nullifies the mpg gain from the ev mode run?
Anyway, the follow-up challenge for me is "BATTERY MANAGEMENT." That's where you make a plan to use coasting, brake riding, or down grades to recharge the battery AFTER a long run in ev mode.