My 2016 Volt has 10.5K miles and is just 1 week short of its 1 year birthday from the day I took possession of it. It has been on its original tank of gas which I have never filled it up, and had a little less than 2 gallons of fuel in it.
A few days ago, the Volt popped up a notification about needing to run maintenance. I assumed it was my usual Engine Maintenance that seems to happen every ~6 weeks, so I clicked the Ok button to let it run. However, the engine kept running for my entire 1 hour commute instead of the typical 10-15 min burn, and my battery was still completely full when I arrived at work.
When I left the office, the notification came up again, and this time I closely read the message and realized it was for "Fuel Maintenance," which I had never seen before. I clicked "More Info" and was greeted with: "Fuel Maintenance: Your fuel usage has been so low that the fuel is becoming stale. The engine must run to burn this fuel. Add fresh fuel when fuel lever is half a tank or less. See Owner's Manual for further details." (see image here
) I tried everything to force the car to use the battery (changing the driving Mode, power cycling the car, clicking the "Dismiss" button), but the car was in a state similar to Hold where it was going to use the gas engine irregardless. I took it as a mechanism to force me to fill up with new fuel. However, I was left wondering what would happen if it ran out of fuel during my drive. Would it swap over to my (completely full) battery? Or would it actually stall out? I didn't want to risk it, so I pulled into a gas station and filled up for the first time ever. Took a picture to memorialize the moment!
My take away is that the car will trigger this unusual notification and engine always-on mode if the fuel hits a 1 year timer. It must also have an algorithm that resets or modifies this expiration timer when new fuel is added (apparently, if you add at least half a tank of new fuel, the timer resets).
Instead of suddenly putting the car into a permanent engine-mode, I would have preferred to have received a notification about the stale gas, and the option to defer the engine-on mode so that I could dictate how and when the car consumes the old fuel and gets refilled up with new fuel. This happened when I was in a crowded urban environment, so the engine was constantly firing on and off, which I would have preferred to avoid. I get that the Chevy engineers had to design the car for casual consumers who may not understand that fuel has a shelf life, but I'm guessing many Volt owners are very technical and would appreciate having more control.