If you choose to precondition, so that the gas engine does not start at colder temperatures you can set the Engine Heat Assist While Plugged In setting to be No so that the gas engine will never run while your Volt is plugged in. You also can set the Engine Heat Assist to Deferred mode so that the gas engine will only come on (once you unplug and manually start your Volt) when the outside temperature is 15 F or below, else by default the gas engine will start whenever you start your the Volt and outside temperature is 35 F or below.