Live MPG meter behavior oddity when car is cold

(Searched for this, didn't find it, feel free to point me to existing thread if I missed it. Have also read entire manual, don't remember this being mentioned.)

So, my ODO is at about 530 miles.

Over the last few days I've noticed a new behavior which I'm concerned might be an indication of something needing to be fixed.

For the first few minutes after the car is started, when I'm rolling forward without my foot on the accelerator the live MPG meter (just to the right of the speedometer) is showing the MPG at around 10 or 15 MPG. This happens with the AC on or off. This happens when the ICE is *not* running.

Until a couple of days ago, rolling forward without my foot on the accelerator *always* showed as 100 MPG.

Do I need to take her in to see a doctor?

 

Oh it runs some during the initial 4 mins or so, but the scenario I'm particularly curious about is the moments when the ICE isn't running (as evinced by my ears, lack of vibration and the display not showing any red arrows.)

 

It's possible i guess.

Still, even if the ICE is on, why would the MPG meter drop all the way down to almost the bottom when I don't have my foot on the accelerator?

Is there a warm-up function that really uses that much gas? And if so, why didn't this happen until over 500 miles on the ODO?

 

Yeah, I'm talking about the live MPG meter to the right of the speedometer, talking about covering a few feet.

Incorrect. If the car is barely moving when it is warmed up the live MPG meter to the right of the speedometer almost always reads 100 mpg. Watch yours after you let off the brake, before you press the accelerator. (If the car isn't cold.)

 

Oh I doubt that. I watch it with quote habitually. Picked up the habit in my 2001 honda insight (which I had to sell in 2003 when a baby was on the way) and fell right back into the habit pulling out of the dealer's lot in my prius.

I'm talking about when I let off the brake and creep forward pulling out of the parking spaced i'd backed into. Getting between 1 to 3 bars in the live mpg meter.

Yes, that's what i'm talking about. Ok, good. Glad it's happening to someone else too. Makes me less concerned.

Right, right, that I get. I'm talking about the live MPG meter though, on the right side of the speedometer. Watch it as you creep forward after letting off the brake, with no accelerator. When the car is cold you'll see (or i do anyway) 1 to 3 bars. After the car is warmed up and you're creeping without the accelerator (like when you're creeping along looking for a parking place) you'll see 100mpg there.

I understand a little less when the car is cold if it's doing a warm-up routine with the ICE, but the discrepancy between 100mpg and 1 to 3 bars (5 to 20mpg?) seems much wider than i'd expect.

 

i get that. what surprising to me is to see the meter wayyy down at the bottom. you can see it much higher with the ICE running without your foot on the accelerator. seeing it around 60mpt or so would make more sense to me. seeing it down between 5mpg and 20mpg is what is causing my confusion. seems like it should be comparable to the mileage you get when you're just creeping forward with the ice running because your battery is low, but it's reaching for the bottom peg instead.

of course, so many posts later i've now spent more time posting about it than I'd spent thinking about it before posting.