Resistance is the same as on flat ground. It shouldn't be making an impact in the whole going up and down the mountain. The amount of resistance you get going 10mi at 60mph is the same going up as going down as going flat. So we're still at you spent some extra energy going up, and now you have that extra energy going down.

I do get if you're needing to ride the brakes a lot you'll get a pretty big impact on range, but a lot of grades wouldn't require that.

>Resistance is the same as on flat ground

At the same speed, but if you don't break you likely won't have a constant speed. There's also motor efficiency, but that has less of an impact on electric vehicles because they are efficient over a high range.

2000ft of elevation change in 35 miles is likely to require braking.

2000ft over 35mi is like a 1% grade. That's not much of a grade.