Prime's Engine Warmup Cycle: Gas Usage?

During the Prime's warmup cycle (once your EV range runs out) how does the non-EV engine warm up? Using gas? Or some kind of non-gas heater? Because if ANY gas at all is used during the warmup cycle, the MPG meter is completely inaccurate.

This has been bugging me for a while, but once the Prime runs out of EV range (0.0) and it begins its gasoline warmup cycle, the pedal immediately feels different, and one noticeably feels the gas(?) coming on. The MPG/Kw/H meter (if set to kw/h during EV mode) immediately changes to show gas MPG -- but for the first 30 or so seconds during the warmup cycle (during which both the gas is supposedly(?) on, as well as drawing from the car's buffer-EV range while warming up), the MPG meter is always completely all the way at the top (199+MPG) even if you're going 65mph at the time -- as if there was NO gasoline being used at all.

In other words, the MPG display is showing what it would show if the car went to temporary all-EV mode for a bit, using NO gas at all. But this can't be accurate, for isn't gas being used during the warmup cycle as well as the buffer EV? Or is the engine warmed up some other way without gas?

If ANY gas is being used (even a little) then the the MPG meter should waver, and won't be rock-solidly all the way at the very top (100+MPG). Yet for those first 30 seconds, it's all the way to the top and doesn't waver at all, no matter what. AFTER the warmup cycle (30-40 seconds), indeed the MPG meter then drops to whatever MPG I'm actually getting at the time -- but for the warmup cycle itself, the MPG meter is indicating no gas being used.

If the Prime's warmup cycle uses no gas at all, then please explain how the warmup cycle warms the engine up after EV range is depleted... I'd be curious to know. (For what it's worth, one feels the difference on the gas pedal as soon as the EV range runs out -- not 30-40 seconds later, at the point when the MPG meter finally drops from showing 100+MPG to an accurate display).

PS: whenever I see the car switching from EV to HV, I like to immediately reset my "TRIP" meter so I can see my gas MPG for the gas part of my trips (if I have, say, 10 miles left that I have to do on gas). But having it be at 199.9 for the first 30 seconds while the car is warming up (but still using gas?) throws off the accuracy of that number more than you might think...

 

I very much appreciate everyone's responses... but can I ask those who actually own the 2017 Prime, to have a look at this situation themselves, and report on how it works in their Prime? (Bob: since you have a Prime, try having a look sometime, and post what you see)

Please note, everyone:

- I do a TRIP RESET as I start out from home for the day in EV Mode (with the real-time monitor showing kw/h, and constantly varying, of course).
- As SOON as the car runs out of EV range some 30ish miles later (and I watch it tick down... 0.2, 0.1, all gone!) I then immediately do a TRIP RESET again (because I want to see what my MPG on gas is for the rest of the trip, from the moment the ICE kicks on).
- As soon as the car's EV range hits "0.0/---" (the point at which I do the TRIP RESET again), the gas pedal suddenly feels sluggish, I can "feel" the gas coming on, and the real-time monitor (that was showing kw/h), immediately switches on its own to MPG.
- However, instead of that monitor showing that at least some gas is being used to warm up the ICE, it instead shoots all the way to the very top (100+MPG) -- and stays there, rock-solid, for about 30 seconds as the car is warming up (as if it was in 100% temporary EV mode, showing NO gas being used at all) -- even as the ICE is using gas for the warmup cycle.
- Immediately after doing that TRIP RESET the moment the warmup cycle starts and I begin to feel the gas usage, the MPG number display will also jump from 0.0 (at the reset) directly to 199.9 (the highest number it will show).
- Only after the warmup process is finished (30+ seconds later), will the real-time MPG meter suddenly drop down to realistic numbers and fluctuate, while the MPG number display will only then slowly start to tick down as well.

But during the entire warmup process as gas is being used, the Prime cheats, and doesn't count any of the gas used to warm up the ICE during the warmup cycle. The MPG number display thus cheats as well, as it includes the distance driven during the warmup cycle when the car indeed did use gas to warm up the ICE -- but didn't report to itself that it used any gas during the warmup cycle.

Just to be clear for those who don't have the Prime: during the Prime's warmup cycle, the car is showing NO gas being used -- it's not just that it's only using a "tiny amount". In normal HV driving, even if I put just a (barely, barely, barely!) featherweight amount of pressure on the gas pedal, the MPG meter may stay in the upper region, but it won't be unmovable/solid at the top -- it'll constantly fluctuate in the upper regions. However during the ICE warmup, the meter is 100% at the very top, not deviating at all, showing absolutely NO gas being used (as gas is indeed being used to warm up the ICE).

Not a big deal in the grand scheme of things I know, but it's something to be aware of. Regardless of how the gasoline is used (whether it's used to move the car or warm up the ICE), if gas is being used in any fashion, the car should show that, when showing you its MPG. Instead, the Prime inaccurately shows NO gas being used AT ALL until the warmup cycle has completed.

 

I'm not trying to be argumentative, honest, but it doesn't seem to correspond to what I see and feel. First, the better measure is the real-time MPG bar-graph (because the MPG numerical display only updates in intervals, not in real time as the MPG bar graph does).

If the car is only using 0.33gal/hr during the warmup cycle as you say, then the car would never be able to sustain 65MPH using only 0.33gal/hr after the warmup cycle is done (and the temporary EV help from the buffer range shuts off), which implies that at the point the warmup cycle is finished (when the temporary EV help from the buffer switches off), it immediately starts drawing a lot more gas to keep the same speed. Ok, that makes sense, and you could be right, except it doesn't feel that way, either physically or visually. In normal (warmed-up HV) driving, putting even the slightest bit of pressure with my foot sends the MPG graph down from a solid "100+" at the top, to wavering around near 100MPG -- but during the warmup I see only 100% absolute solid at the top, never wavering. When the warmup cycle first starts (and gas first starts being used) there's quite a physical change in speed and additional pedal pressure needed to keep the same speed -- it's quite obvious and noticeable... and the change in additional pedal pressure needed to keep the same speed as the gas comes on doesn't seem like it would be there if it was still almost all EV (the mode you're coming out of), and only a tiny 0.33gal/hr of gas being used. Then as the warmup cycle ends (at which point, if I understand what you're saying, you think a lot more gas supposedly immediately starts being used) there's no feel at all of that extra gas being used.

I could be wrong, but it certainly feels as if the big change is when the warmup cycle starts and the gauges just aren't reflecting it. If I'm wrong, then it's a great illusion with the car (the lurch, and additional pedal pressure suddenly needed to keep the same speed the moment the warmup cycle starts, but no noticeable change at the end).