Engine maintenance on plug-in hybrid vs. regular vehicle

Question

Plug-in hybrid vehicles have enough power to cover 100% of my daily commute. Driving on electricity alone and not having to run the gasoline engine greatly appeals to me, but I also understand that the engine should be used from time-to-time to ensure its longevity.

The answers to these questions sufficiently explain how to keep a rarely used gasoline engine in working order, but the answers, except in the first question listed, are a few years old and with regard to regular cars.

Is it okay to leave a car outside in the winter without driving it for 1 month?
Is it okay to leave a car for 5 months without driving it?
How to maintain a sometimes-used vehicle?
How long does it take for gas to go bad?

(In summary, the answers say that the gas should have a stabilizer added if it will be sitting for more than 6 months, and that the engine should be run for at moderate amount of time every couple of weeks to burn off the condensation.)

What I'm wondering is, do these same principles apply to plug-in hybrids? In other words, is there a difference between maintaining an unused gasoline engine on a plug-in hybrid driven daily, and a standard vehicle not driven at all?

I hope there is an answer that is generic to most vehicles, but calling out a specific make and model is fine. Examples include the Chevy Volt, Hyundai Ioniq, and Toyota Prius Prime.

Answer 1

While it is true that, as a previous answer said, all the same systems exist and need to be maintained as in a pure gasoline car, it is also the case that in the Chevrolet Volt (first and second generation, 2012-2018), there are automatic functions to maintain the life of the engine and fuel.

• The fuel tank is sealed and pressurized (rather than vented to atmosphere) to extend the life of the gasoline (so it will do better than standard recommendations).

• Fuel Maintenance Mode: The car tracks the average age of the fuel in the tank and decides when it is too old. Then it will prompt you to either burn off the old fuel entirely or add new fuel which will mix in (or both).

  (Thus, it is wise not to fill up all the way if you're not expecting to use it, but you can easily keep around enough gas to double your range and not have to worry about running out of battery power, and make a fuel stop before or doing a long trip. But if you don't plan your fuel storage at all, the worst that will happen — assuming the car is driven regularly — is that you will use gas instead of battery power when you didn't need to.)

• Engine Maintenance Mode: The car tracks time since the engine has last run and will run the engine for about 15 minutes when it has been a while. You can temporarily defer this in case you know you are making a trip too short to finish maintenance.

In general, you do not have to worry about the sitting-idle implications of owning a plug-in hybrid — the Volt takes care of them for you.

I cannot comment on how the Hyundai Ioniq and Toyota Prius Prime handle these situations; they weren't models I researched before I bought my Volt.

Answer 2

There's no difference, the engine, fuel system, ignition system, etc. are all the same as any non-hybrid car. The only difference is that the engine is run on demand for charge rather than responding to throttle input. The advice doesn't change.

Running the engine once per week will keep things in order, and you won't need to add a stabilizer as you'll use up a tank in 6 months.