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Discussion Starter #1
hi.

I am new to this forum and spent about 20 minutes scanning entries looking for something to discuss my area of concern. I am sure this is not a new issue, but since I am new to the forum, it is new for me...

I bought a prius Oct of last year. My gas milliage is about half of the advertized milliage... 31 to 35 mpg. I have talked to other prius owners in my area and they are averaging 42 to 47. I took it to the dealer to find out what is wrong, but all they did was detail my car and give it back to me. I don't think their "prius mechanic" has any clue how to diagnose/deal with non-oil change/tune-up problems.

Anyhow, form what I have heard from others, I am doing everything correctly.. start/stop slowly/gently, keep an even pressure on teh gas pettle as much as possible, drive wiht my windows rolled up to increase areodynamics, tire pressure ok, etc. I also noticed that
* the milliage monitor is very inaccurate to what the milliage really is. It varies from about 30 to 40 MPG avg per tank, but usually it is off plus or minus 5 MPG from actual miles driven divided by gallons of gas input at pump.
* the city street milliage is very dismal... usually about 8 to 13 miles per gallion. Heck, my old madza rx7 (the car I replaced with the prius0 did better than that.
* the engine rarely turns off when stopped at a light or stopped for any other reason

I am firmly convnced that something is wrong with my car.. like a lemon or something. But I don't know how to proceed to get it fixed. I really think it shoudl be doing better than 30-35 MPG, especially when others in my area are getting 42-47....

And ideas/insights/advice would be much appreciated!
 

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Up until you mentioned that your engine hardly turns off, even at stop signs, I was pretty much thinking your experience is similar to mine. You didn't post your area, around here with short jaunts, I am often under 40mpg--as an average. At stop signs, though, and in traffic, the battery kicks in and I do really well--up to 75mpg for some 5 minute time periods. I'd mention the ICE problem and see if you get a different response. However, posters such as mrv, Dan, and others are technically savvy and should be able to give you better insight.
 

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If you are truly driving as you say you are, you should be getting much better mileage. And if your dealer can't help you, try another dealer.
 

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low mpg

I have all the usual concerns: Perhaps you are taking mostly short trips so the car cannot exit warmup mode, your engine oil may be overfilled, or your emergency/parking brakes may be dragging. Change the $20 engine air filter, just 'cuz I said so. You already said that the tires are not flat.

Perhaps the air conditioning or defrosters are always on? Someone with the new model Prius will have to help with those details; that car baffles me.

In my experience, even relatively good Toyota shops will not always look closely at complaints like this. I suggest that you post your location and buddy up with another Prius driver in your area. We ought to be able to get you up into the 40's, anyway.

DAS
 

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How long - in minutes - is your typical drive? If it's around 10, then the car isn't getting fully warmed up, especially if you live in a cold climate. The Prius gets mediocre (for a Prius) mpg in the first few minutes, while the engine and catalytic converter warm up.

That's the only way I can see a properly tuned Prius getting such poor mpg.
 

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P.S. - The discrepancy between the mpg on the screen and the mpg calculated at the pump is completely normal. (Unfortunately.) That's because it's very difficult to get a consistent fill level on the Prius - so the pump calclulation is liable to be inaccurate for any given tank. Over time you'll see that the two calculations are quite close overall.
 

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I too believe you may be running extremely short trips. As for your engine not shutting down on these trips, try this: When you start your car (go into READY), wait for the obligatory engine warmup start, then wait about a minute or two and the engine should stop. At this point the ICE should be more willing to shut down at traffic stops, but may still run to get itself to optimal operating temperature. The first 5-10 minutes are the worst for mileage, about 35-40 MPG average but still a heck of alot better than a conventionaly car. Conventional cars have that warmup period too, but may not be as agressive since they are always running anyway.

Tire pressure: Factory specs indicate 35F/33R, but you would do much better with at least 40F/38R. Tire wear will probably be better, though your ride will be a bit rougher.

Oil level: I used to think it was a factor if the engine oil was over-filled. Gross overfill will, but I don't think the 1/4 quart that is typical will matter much. Certainly not 10-20 MPG! Maybe 2 MPG at most if any.

AC: Now in any car, this can be a major factor. Moving heat from one place to another takes energy, no matter how you slice it. The new Prius is much more efficient at it since it runs the AC at various speeds to match the heat transfer load. Using electricity to run the AC allows for the compressor speed variation, and also allows the ICE to defer providing power to the compressor until you driving, where the engine efficiency is greater than at idle RPMs.

Battery SOC: If your car is doing more stop than go, your battery's state of charge (SOC) can get quite low. The battery is a buffer, not an orginating energy source. If you take from it more than you put in, it gets depleted. When it gets low, ICE has to run more often to provide the power you need to get going. This is especially true if the AC is running hard.

I believe you will find that under the same exact conditions which includes climate control and traffic patterns, your Prius is doing much better than any other similar sized conventional car would.

Take the car on a nice pleasure trip on the highway for an hour. Also try driving on secondary arteries where speeds aren't as great but when traffic is light and you'll see that the car is capable of 50 even 60 MPG.

As for the screen, short term single tank comparisons aren't going to work since you can't be certain you filled the tank to the same level you started with. Over long term, you will find the display more accurate. However, there will be a small difference. I nearly consistenly see the display read about a 2 MPG overoptimisticly @ 55 MPG.
 

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Read this article....twice:
http://priuschat.com/index.php?autocom= ... ticle&id=3

Then reset the mpg on the consumption screen and take your car out for a leisurely 1 hour drive on rural roads at around 45mph. Avoid hard or abrupt braking, use the cruise control, keep the AC off or at a comfortable but not cold temp (I use 78 degrees and find it keeps me comfortable) and see what your mileage does for that trip. If you're not in the 50s then I'll believe that there might be something wrong with the car...but I doubt it.
 

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Read the owner's manual. Skip the parts that talk about options not in your car. Betcha a nickel you find something relevant to fuel economy that you didn't know.
 

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Discussion Starter #11
More Info

Thank you guys for your suggestions. I noticed that a lot of you wanted more info (things it never occurred to me are relevent when I wrote my post). Here are some of them

* My average drive time is usually about 20 minutes to 30 minutes each direction.

* I live in the San Francisco Bay Area (Oakland) so my climate is very mild. However, I did notice that on overcase/rainy days, my milliage is not as good as on nice sunny days.

* I keep my autocontrol on 80 degrees on hot days and on about 70 on cold ones. I do that intentionally to not overuse the auto air conditioning system.

* I never drive with the windows open ... I don't like open windows blowing things around the car. I was happy to find that this is also better for gas milliage because of the aerodynamics. (I guess I lucked into that one).

* Uusually I am the only passanger in the car and I weight about 170 lbs. Sometimes hubby and I go somewhere together and he weights about 200 lbs. My dog occasionally goes with me (in the back) and he weighs bout 95 lbs. But most of the time it is just me in the car, and I don't haul heavy stuff.

* I do live in the oakland hills. The first 1.5 miles from my house is steep downhill when leaving (tends to get the 99 mpg) and when I drive home, that climb tends to average about 8 mpg for that 1.5 miles. My average trip is about 10 miles city or 20 miles freeway, dependingon where I am going. (Nothing is close ot my house) I also do a lot of driving to San Jose (freeway for about 50 minutes). I really do get much better gas milliage on the freeway than on city streets. Most of the time I drive on relatively flat roads but my trip home always ends with a steep 1.5 miles up a hill cuz I live on top of that hill.

* I don't usually warm the car up before moving -- never occurred ot me and is not really condusive to my lifestyle as I am usually running a few minutes late by the time I hop in the car. I will try intentionally leaving a few minutes earlier and waiting 3 or 4 minutes for it to warm up.

* someone mentioned the battery charge monitor. It very rarely ever goes down to half changred and I have only seen it go below half chanrged once. Does that mean that the battery is niot kicing in as often as it should? Most of the time the batter carries about 2/3 of it's charge, going up/down by about 2 bars.

* during the winter (rainy season) I was driving with my headlights on a lot during the day because the CA law requires that if you have your windsheild wipers on, you must also have your headlights on. It was easier to just drive with them on than to worry about turning them on/off each time I hit the wipers as it was constantly drizzelig or raining for a couple of monhtes. Does having the headlights on efffect gas millage noticably?

I am still not 100% convinced that the car is functioning properly, bt I am willing to do whatever I can to try and get the millage up to at least over 40 (it has never once been over 40) and preferable ot the 45 to 45 that most of the other peopel who live near me seem to be getting.
 

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Discussion Starter #12
one more thing.... logging Gas milliage

I have been keeping a handwritten log every since I got the car of the mills driven and the number of gallons of gas the car took at the pump. While any one fill up may be slightly off, the fact that I have been trackng that since I first owned the car makes me feel pretty confident of my milliage tracking.

BTW, I will try increasing the air pressure in the tires to 40/38 as per Dan's suggestion. the mechanic at one dealership also suggested that but the mechanic at another dealership told me that if I overfill my tires to that pressure, they will pop the first time I run over something on the road) so I have been keeping them at 34/32 (front/back).
 

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Re: one more thing.... logging Gas milliage

t.e.s said:
the mechanic at another dealership told me that if I overfill my tires to that pressure, they will pop the first time I run over something on the road)
I'd buy that if you were filling the tires well over the max pressure listed on the side of the tire, but in the case of the OEM tires the max pressure is 44psi so going 40/38 (as I have mine) should not pose any problem.
 

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t.e.s.,

I used to live on Bayo Vista, in the Oakland Hills, so I think I know the area that you drive.

I currently live in the hills above San Diego, and except for the distance (I drive 47 miles one way in about 65-75 minutes each way) my commute is similar to yours. My lifetime average is 49.7mpg over 23,700 miles. My worst was 43 and the best was a 64. (I had 2 'flukes' of 36 and 77, but I think that was due to operator error on my part :? )

As to prewarming the car, I don't do that and I think others will note that there is really nothing to gain. (It is not like the bay Area is like Michigan during lake effect snow storms and drifts :lol: ).

For reference, I hit 2-3 steep grades in my commute as well, but my mpgs never hit 8-9mpg like you describe.

To add some more questions to those noted:

Have you had the emergency brake checked to see if it is dragging?

Is the car aligned (have you noticed any 'crabbing'? do you constantly have to correct the steering a lot, like the car always wants to drift left or right?)

How many total miles have you on the odometer?

I suspect that you may have to seek out a different shop; perhaps there is a computer update that is incomplete or needs to be reset to specs.

Walt
 

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Note this. Currently I'm averaging about 48 mpg because I stop to pick up my sister on the way to work, there is an incline (no more than 1 mile in either direction) that I truly believe is what causes my lowered mpg--it is driven at the posted MPH (says 45, I drive around 47)--my "mpg" during this is usually at 15-16 according to the screen. When I was not picking her up (my sister) and was able to stay on the highway and avoid this heinous hill, I was averaging about 52mpg on those tanks. I can have excellent MPG and everytime I hit that hill I notice that it takes my average down. Now that I've had about 800 miles on the tank, it only takes it down .1 or .2 but its still enough (over time) to lower my average MPG, which could be the case for you.
 

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The easy way to see how much of a difference the hills are making is to take a Saturday and go drive to somewhere flat, then do a little driving exactly how you do during your normal commute otherwise, and see what you get.
 

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Release the parking brake.

Case closed. :wink:
 

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Hep said:
Release the parking brake.

Case closed. :wink:

Been there, done that too, eh 8) 8)

Quick quiz:

How do you know when the chocks and chains are in place on your jet?

Answer: When it takes full power to taxi
 

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Discussion Starter #19
someone wrote "release the parking break..case closed."

Would that it were that simple!!!
 

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I think you may have missed one of my suggestions in 'warming up' the car.

The ICE starts about 7 seconds after you put it into ready. If you drive right then, the computers may be reluctant to turn ICE off at stops if it isn't warmed up yet or even if it is if the stops are only a few seconds. If you wait a minute or two for the ICE to actually stop, the computers will be more receptive to shutting ICE off at stops. At least it appears to do this. It has to do with the speculated stages the computers put the car in for its behavior.

Overcast should give you better mileage, not worse since the AC doesn't have to deal with sun heating of the cabin. Rain causes wet roads which increases drag so I understand a drop in mileage there.

SOC during normal operation will try to keep to 6 bars. Extra power required for long steep hills and/or acceleration could bring SOC down. If the car is not moving, the computers will allow the SOC to drop to 2 or even 1 bar in the hopes that you will get moving again and it can charge using more efficient RPM band of ICE. When SOC gets low in heavy slow traffic especially with heavy AC (which is common for me on US19 after work in this heat), ICE may run more frequently even when stopped.

But it sounds like your SOC is optimal for good MPG.
 
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