Once you hit limp mode in the
Once you hit limp mode in the BMW i3 you will know what other have talked about.
I have driven the volt in the mountains, as well as an Escape Hybrid and an I3.
They can all hit limp mode. In the escape, after a short hill climb the limiter comes on and you can't get past 55. On the volt, IF you enter mountain mode a few miles before you hit the mountains, you will probably never hit limp mode buy if you don't, after a few miles of heavy accelerating up the grade, the dreaded warning message comes on, and the speed gets limited. The car starts to slow down, and levels off between 50 and 55MPH. So it is important to put the volt in mountain mode 5 to 10 minutes before getting to the hills. That way the generator can spin up faster, and build a 10 mile buffer up in the battery. It takes 10 minutes to put a 25% reserve charge in the battery, but it will never run out of power when you do this.