You have to think of the Volt as a pure electric car, until you have used the battery to its minimum. Then think of the Volt as a hybrid. The engine starts at that point and runs just hard enough to maintain that minimum charge. You can force a higher state of charge into the battery by selecting hold mode, or Mountain mode. In those cases the engine will run at higher RPM and power to charge up the battery. You will obtain some battery reserve but not a full battery with the engine running and selecting hold, or mountain. Most advice is to not overthink it. Just get in and drive wherever you need to go, local or highway. Plug it in when you can, put gas in when needed.