GM designed this car to take care of itself. There are TWO modes used to do this
MY 2017 just went through the FMM this past June when it forced me to burn off all the gas the dealer put it when my Volt was delivered in Aug 2016. For me it was a waste of 6 gallons of gas.
Also suggest down loading the Owners Manual PDF from Chevrolet's web page.
Good luck and welcome aboard. BTW where are you located.