Here's the writeup I did on my experiences with not needing Mountain Mode.
www.gm-volt.com
Mountain Mode not needed (Gen 2)
It's leaf peeping season in Colorado, so this morning I filled my tank and headed for the mountains. I live at 5,700 ft above sea level and ran out of battery after a little over 47 miles and a net climb of 2,800 ft. I stayed in Normal mode the entire loop, driving over Kenosha Pass at 10,000...