New to a 2012 Volt. Is there a way to add battery "Hold"???

Welcome to the club! Other 2011-2012 members use mountain mode as a "modified" hold mode. It will keep the charge to around 1/3 or so remaining of your normal usage. It's not as helpful as a hold mode that will sustain the charge at any other times you choose, but it may provide some usefulness on a longer trip where you expect that perhaps your last 1/3 of the miles will be at lower speeds. You can select "Mountain Mode" when you have about 1/3 or so left and the Volt will "hold" the charge. You can then switch to "Normal" when you want to go back to CD mode. I would invite the early adopters to weigh in on the best use of it as I bought the first year, 2013, that hold mode was available.