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I have recorded & computed my mileage for every tank full for every car that I have ever owned. For my 07 Prius, I've averaged 49.1 mpg (computed), with a low of 32.2 and a high of 69.1 for a single tank of fuel, since mile1. The computed average of the displayed mpg is 50.5.

I'm not sure that "green leaf cars" (I think they look like little green turtles) necessarily indicate too much braking. Recharging also occurs w/o braking. Last week (after my 50K service, so everything was "in order") I noticed 5 "green cars" in a 25 minute span (5 min screen) while driving about 20 miles on a 2 lane rural state highway with very little braking. There were maybe 3 traffic lights (& very little traffic) during that time. A couple of days later there were 3 "cars" within 20 minutes while driving on an Interstate highway.

I suggest that you hit "reset" on the display when you fill up your fuel tank. That will reset both the mileage and mpg. I "think" that the mpg displayed keeps computing (from last reset). I also "think" that my mileage auto-resets after fueling . . . I always reset, so I don't remember. It takes very high mpg (over several tank fulls) to make even a slight increase in the average when the computation is spread over 10,000 miles. Maybe you just need to restart your calculations.:Bruce:
The leaf cars only show regenerative braking and not recharge by the engine so i'm not sure how you're getting regen on the highway unless you are braking or even just coasting (1 min consumption screen will show 30kWh leaf cars while the 5 min cons. shows 50kWh per leaf car so keep in mind that the numbers the leaf car represents changes depending on which Cons. screen you're on).
 

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. . . (1 min consumption screen will show 30kWh leaf cars while the 5 min cons. shows 50kWh per leaf car so keep in mind that the numbers the leaf car represents changes depending on which Cons. screen you're on).
I only have 1 screen (Consumption, I think it is) on my 2007, so whatever each car represents. It is what it is. My point was that I get leaf cars w/o excessive braking, as was suggested in an earlier post.:Bruce:
 

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Prius
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The '07 Prius would've had 5 min consumption screens.

Oh it doesn't take much to regenerate 50kWh. (you said 5 in 25 so I assume ~1 leaf car per 5 min segment)
 

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I know this is an old thread, but I've had a 2010 Prius for a year now, and we've never gotten over 44mpg. Ever. Only got 38mpg on the last tank. 90% city driving at speeds of 30 to 45 mph. The best I've ever gotten was 44 mpg on a interstate hwy trip of 600 miles, with the cruise set at 65. Bought it with 72K miles, now it has about 86K.

I've read all the poor gas mileage threads here (posting in this one because the OP had the same car and MPG as me) and have tried premium/non-ethanol gas, increasing tire pressure to 40lbs front and rear, ensuring the oil is synthetic 0w20 (changed it myself last time - just in case), new air filter, letting bicycles out race me from a stop to the next light, etc.

Nothing seems to make much of a difference. If I REALLY baby it in city traffic and go slower than molasses in Jan, coasting between lights, (getting outrun by bicyclists - literally) etc, I can get 44 mpg.

Don't get me wrong, 38 mpg isn't terrible, but it's basically the same as what I get in my 2002 ZX2 on the hwy at the same speed. Hell, it isn't that much better than my 4-banger '99 s10/5spd that gets 30 mpg hwy. I've always been able to beat the EPA estimates in ever car I've owned. Something has to be wrong... There are no codes, dealer says everything is fine. BS.

What else could possibly cause the mpg to be this low?
 

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Where you drive?

Stop and go "city" driving requires a lot of starting of the ICE. You run on the battery for a while, then it needs to be charged so the ICE starts. Plus where you live and its climate demands for HVAC can affect mileage. Short trips mean the ICE engine is always warming up (remember the old cars with chokes so you could rich out the mix of air/fuel for starting. Modern fuel injection is more efficient but still...).

I use fuelly.com to compute my MPG, not the cars computer. And even it is sometimes wildly off because of the variability of a gas pump in one station versus another. Imagine the fuel shut off being just .1 gal off between pumps. But over dozens of tanks it gets it closer to right and you can see patterns. Where the weather got you, where being in a hurry cost you. Where having a full car and trunk cost you. I don't get at 72mph what EPA got at 55. But overall I'm close enough to the EPA figures not to worry. After all I'm getting twice what my prior same-function car got.
 

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I know this is an old thread, but I've had a 2010 Prius for a year now, and we've never gotten over 44mpg. Ever. Only got 38mpg on the last tank. 90% city driving at speeds of 30 to 45 mph. The best I've ever gotten was 44 mpg on a interstate hwy trip of 600 miles, with the cruise set at 65. Bought it with 72K miles, now it has about 86K.

I've read all the poor gas mileage threads here (posting in this one because the OP had the same car and MPG as me) and have tried premium/non-ethanol gas, increasing tire pressure to 40lbs front and rear, ensuring the oil is synthetic 0w20 (changed it myself last time - just in case), new air filter, letting bicycles out race me from a stop to the next light, etc.

Nothing seems to make much of a difference. If I REALLY baby it in city traffic and go slower than molasses in Jan, coasting between lights, (getting outrun by bicyclists - literally) etc, I can get 44 mpg.

Don't get me wrong, 38 mpg isn't terrible, but it's basically the same as what I get in my 2002 ZX2 on the hwy at the same speed. Hell, it isn't that much better than my 4-banger '99 s10/5spd that gets 30 mpg hwy. I've always been able to beat the EPA estimates in ever car I've owned. Something has to be wrong... There are no codes, dealer says everything is fine. BS.

What else could possibly cause the mpg to be this low?
A weak or failing auxiliary (12V) battery will cause the symptoms you're describing except that you've had the problem for a year. At the very least. have it checked by a reputable mechanic to see if it is dying. You'd eliminate one more possibility.
 

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Prius
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Other things you could check include wheel alignment and maybe flushing out the fuel lines and spark plugs with fuel injector cleaner (just grab a bottle or two from the dealer and put it into a full tank and the other 2 tanks later).

38mpg to me is terrible considering that's what I get if when it's -30°C or colder (All it takes is one or two days at those temps or colder and my tank average is a goner). My worst tank was 37mpg calculated and that's when it hit -46°C at the airport (-35°C in and around the city).

44mpg seems ok if you're not babying it and driving it like a regular car (so no consideration for heat or A/C consumption cause reducing the need for a toasty or ice cold interior will help increase fuel economy).


You should be around 47mpg at 70mph (give or take) and highway mileage smooths out the inconsistencies since you're at a steady speed and hopefully in reasonably flat terrain with minimal head or tail wind to mess up the calculation.

Have you tried a different station or different fuel company (you'll have to try it over several tanks to get an average).

Worse come to worse, you could reflash the ECU to reset it to the factory setting to undo whatever the previous owner did (maybe he consistently used crappy fuel so the car was compensating).
 

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Other things you could check include wheel alignment and maybe flushing out the fuel lines and spark plugs with fuel injector cleaner (just grab a bottle or two from the dealer and put it into a full tank and the other 2 tanks later).

38mpg to me is terrible considering that's what I get if when it's -30°C or colder (All it takes is one or two days at those temps or colder and my tank average is a goner). My worst tank was 37mpg calculated and that's when it hit -46°C at the airport (-35°C in and around the city).

44mpg seems ok if you're not babying it and driving it like a regular car (so no consideration for heat or A/C consumption cause reducing the need for a toasty or ice cold interior will help increase fuel economy).


You should be around 47mpg at 70mph (give or take) and highway mileage smooths out the inconsistencies since you're at a steady speed and hopefully in reasonably flat terrain with minimal head or tail wind to mess up the calculation.

Have you tried a different station or different fuel company (you'll have to try it over several tanks to get an average).

Worse come to worse, you could reflash the ECU to reset it to the factory setting to undo whatever the previous owner did (maybe he consistently used crappy fuel so the car was compensating).
I live in Eastern Tennessee, so weather extremes (other than the last 2 days!) are really rare. around 25 to 35 for lows in the winter, with winter highs in the 40's and 50's. Summertime highs are rarely above 90.

I have run fuel injector cleaner through it a couple of times, but I have not had an alignment done. I also haven't even checked the plugs - gotta put that on the to do list....

Terrain here is decidedly not flat, but it should basically even out - after all, the hills we go up one way are downhill coming back. That being said, we don't drive into the mountains much, so the hills I'm referring to are just a few hundred feet high.

Thanks for the suggestions!
 

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Prius
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No prob!

Actually rolling hills are best for mpg as you can take advantage of the descents to make it partially up the other side rather than just gliding (no arrows to/from the battery) on a flat area where eventually you'll slow down.
 

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2013 XLE Hybrid
2004 Prius
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It's the combo of cold temps, winter fuel and other disinterested third parties. I, too, see a drastic drop in fuel mileage every winter. Plus, the engine runs more to keep the oxygen/fuel ratio sensor hot and happy (no signal until warm, even with a heated sensor).
Don't worry, your mileage will magically return when the air temp rises. It does for me every year. And this winter has been very hard on every thing .


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