And the range extender was underpowered. Drive up a hill on a freeway at 70 mph and the battery would deplete and the car would slow down to 25 mph which was the fastest the range extender could make it go up a gentle incline.

It's dangerous to do 25 mph on a freeway... There are some roads I'm too scared to drive my i3 on now.

If you pulled over to let it recharge, it wouldn't do so, since the range extender refuses to run at full throttle when the car isn't moving fast (perhaps no cooling fan??)

Yup, my friends had one and loved it despite the... unique styling.

They live in the Puget Sound area, and both work at the same place. It worked out to where they could do their commute, and ordinary errands entirely on battery, and only needed the range extender if they were going into downtown Seattle or on a road trip or such.