We took a long weekend driving across the Smoky Mountains. A few observations: -Climbing a mountain in EV mode uses battery very quickly. On the other hand, coming down the mountain, we actually generated more electricity that we used. Running in EV mode the entire way down (~29 miles), my EV range increased from 11 to 39. This is a combination of adding charge to the battery (from 0 to 50%) and the KW/mile number becoming very low. I wonder how the car handles the EV range calculation when the KW/mile is a negative number? In theory, the range could be infinite since the car does not know how long you will be going downhill. -On a long trip in HV mode, it is best to maintain the battery charge in 40-60% range. With zero EV range (2 bars showing), the engine sounds like a swarm of bees while going up a long grade. My wife kept asking what's wrong with the car? It makes for a very unpleasant driving experience. With 50% charge and going up same hills, you hear the ICE, but the sound is more like a normal car engine and nowhere near as annoying. -The Clarity handles surprisingly well on mountain roads, but the eco-tires are not up the task of turning all that weight. I think a good set of more performance oriented tires would help a lot. I wonder what the impact to range would be? -This morning after full charge overnight, my EV range was showing 59.5, the highest it has ever been. (Previous high was 45.) I know it is warmer today, but the car must be remembering the low KW/mile number from driving down the mountain, even though the car drove 100+ miles in HV mode on highway after that. Question for Volt owners - after the battery is depleted and you are climbing a mountain, does the engine sound like the Clarity does?