I have made many trips through mountain ranges (I live in Colorado) and I would recommend using hold mode while climbing in elevation. When you get to the top, switch to normal mode and let the car regen on the way down, leaving cruise control set and transmission in normal drive, not L. On a trip from my home to Las Vegas, NV, even though I used hold mode instead of mountain mode, some EV range was depleted, but easily recovered on the downhill runs. I simply kept the car in hold mode until the car was using 5kwh or less, then I’d switch to normal mode, and cycled that way the whole trip. Mountain mode in Gen 2 is not as effective as it was in Gen 1. Gen 2 saves roughly 20%, but isn’t as efficient at keeping up the 20% level. Gen 1 saved 50% and was far more effective at keeping the 50% stored for mountain driving. Anyway, I plugged in at my hotel in Vegas, and had 85 miles of EV range in the morning when I left to head for California. I was only able to get 58 miles of EV driving from the 85 projected miles, but I was also driving 80 mph for parts of the EV trip.