Mountain driving with studded snow tires

Just got a new Prius C about a month ago. So far, I've been averaging 47.5mpg since buying it. It is largely a mix of mountain canyons (4,000 feet elevation gain to my house from town) and some flatland highways -- not a lot of city. I got 55mpg on a longer trip, all through the mountains. Usually says 99mpg going down to town, and around 27mpg going back up to my house. I'm running 185/65/R15 iPike studded snow tires on it (I live at 9,300 feet elevation, and we have icy snowy roads about 5 months a year) and they do seem to have dropped the mileage a little from the ones that came on it. I haven't increased the tire pressure from the tire store's 32psi, so that'll probably help a little... I always ran my subaru tires at near max, to keep the wear even (at lower pressures, the sides wear out faster, from all the cornering in the canyons). Haven't had actual snow yet, to see how it does in that.

A couple of things I've noticed.... if the battery is full, it'll stay in EV mode up to 40mph or higher, if you keep a very light pedal. After coming down the mountain into town, It goes into EV mode, and I can get a mile or so into town if traffic allows, without having the engine come on -- going at speeds up to maybe 45mph. Just have to accelerate very slowly off of the lights.

Also.... the average battery level when I drive it is much higher than when my girlfriend drives it. Sometimes she has it down to 2 bars. I almost never get it below half -- and that's coming up the canyon pretty fast. Hmmmmm. I usually average 1 to 2mpg better than her on the same route. though she's increasing her average with practice. I'd like to figure out how to make it go down farther sometimes, because sometimes I know I'm going to be going down a big hill soon and I'll run out of battery room for regen -- you can tell when the battery gets full, it doesn't feel the same in regen, especially in B mode on the hills -- if there was a way to tell it to use more from the battery on the previous uphill to have more room in it for the coming downhill, that would be nice.

Overall, this car is awesome... first new car I've ever bought, and I'm enjoying getting twice the fuel economy of the subaru, and three to four times what any of my trucks gets. I like the bright orange color too