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Toyota Prius MPG-Real World Numbers

767 messages,  Last post on Sep 28, 2009 at 9:21 AM

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What is this discussion about? Toyota Prius, Hybrid Cars, Fuel Efficiency (MPG), Sedan


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#637 of 767
Re: Calculated vs Car figures [phd86] by prius2007
Oct 29, 2008 (6:07 am)
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Replying to: phd86 (Oct 28, 2008 6:44 pm)

phd86:
re"Nobody gets even 50 mpg, and none of them post on edmunds."
  
Is that so?!!! Then what is this:
link title
http://www.edmunds.com/toyota/prius/2009/consumerreview.html
 
HMMM phd really does mean "Pile it Higher and Deeper"!!!
#638 of 767
Real Miles by oldcoach
Oct 29, 2008 (7:45 am)
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I have a 2008 prius with pg 2 and have driven just over 5000 miles and my real MPG is 48.6.
#639 of 767
Re: Calculated vs Car figures [prius2007] by kdhspyder
Oct 29, 2008 (9:36 am)
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Replying to: prius2007 (Oct 27, 2008 6:46 pm)

Further on your point one has to be aware of the 'forest and trees' concept. Watching each and every tank average on the MFD is not really useful for all the reasons that you noted above. It is a best an indicator. The only real values that should be used are miles driven / gallons pumped. Nothing else matters.
 
Due to variabilites beyond our control from the gas station to the fuel tank/bladder to the outside environment watching one tank or another is far too specific ( looking at a tree ) to have any concern. Only after accumulating a sufficient amount of data can one really determine what the vehicle truly is using in fuel. This will take a year or two ( the forest ). And the result will be be about 47-48 mpg.
 
A couple of other important suggestions:
1. Short trips are death on fuel economy. You can see this on your MFD every day that you drive. Look at the first 5 min bar on the CONSUMPTION screen. It will almost always be 25-35 mpg. THIS is the anchor that is holding down your average fuel economy. Having to overcome this first 5 min of relatively inefficient driving brings down your daily/weekly average. DON'T TAKE SHORT TRIPS!!!!!
 
2. DON'T STOP - EVER!!!! This may seem ridiculous but no vehicle can overcome Newton's First Law of Physics. Succinctly a body at rest will remain at rest unless a superior force overcomes it's inertia. When you come to a stop light or stop sign normally you will stop the vehicle. It takes a huge amount of energy to get the vehicle rolling again. That energy always comes from the ICE through burning fuel. Now some of it may have been stored in the battery previously so it's the stored energy that first gets you rolling away from a light but all that does is deplete the battery quickly such that the ICE has tokick in sooner and replace the used energy in the battery reserve.
 
You will likely get your best fuel economy on a 30-60 min trip where you never have to stop and you must keep to driving at about 35 mph due to traffic or to road laws. I've averaged 65 mpg for such a 50 mi trip.
 
93,000 miles with a lifetime average of 2.1 gpc used ( 47.9 mpg ).
#640 of 767
Re: Calculated vs Car figures [phd86] by jana6
Oct 30, 2008 (4:35 pm)
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Replying to: phd86 (Oct 28, 2008 6:44 pm)

Thanks phd86. And I do think you are right that a lot of people don't get above 50 mpg. I checked out the one file (adobe) and read all it had to say. I really understand better why I'm not getting the 50+ mpg and that does make me feel better too. My drive to work every day is only 15-20 minutes and I do a lot of short trips to the store, etc. As for actual vs what the computer says, I've been keeping track since about March and I'm going to put together a spreadsheet to see what it averages and to show the dealer. For me, there is a big difference between the two and the actual is normally quite a bit less than the computer. I would think it should average out. I understand about the bladder, not filling it completely full, etc but... Again, thanks for your reply.
#641 of 767
Re: Calculated vs Car figures [cdhc] by jana6
Oct 30, 2008 (4:41 pm)
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Replying to: cdhc (Oct 24, 2008 5:11 pm)

I read through the Adobe article as well as your info again and thank you. I do have a question. Why is it better to glide than to coast when coasting charges the battery? Isn't charging the battery better in the long run? Shouldn't the Energy Monitor battery showing green vs blue best?
#642 of 767
Re: Calculated vs Car figures [kdhspyder] by prius2007
Oct 31, 2008 (5:32 am)
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Replying to: kdhspyder (Oct 29, 2008 9:36 am)

re: "A couple of other important suggestions:
  
2. DON'T STOP - EVER!!!! This may seem ridiculous ...When you come to a stop light or stop sign normally you will stop the vehicle. It takes a huge amount of energy to get the vehicle rolling again.
  
You will likely get your best fuel economy on a 30-60 min trip where you never have to stop and you must keep to driving at about 35 mph due to traffic or to road laws."
 
Thanks for the great advice spyder! "Don't stop - ever" ... "normally you would stop...". You must have a lot of followers, based on my observation of driving behaviour.
 
Can you please help me with my mileage? I'm struggling
 
So far have driven 26,999 miles since Apr 2007 and pumped 455.46 US gallons of fuel. No matter how hard I try I can't average " And the result will be be about 47-48 mpg". I can't even get that on a single tank let alone overall. Can you help me out please?
 
I do stop when I have to (stop signs/light ...) and I do take frequent longer trips than the 30-60 minutes you stated as best for MPG. I admit driving on the HWY (50% of my driving is HWY) and do go up to and over 60 MPH. Are these the reasons why I can't get your predicted 47-48 MPG?
 
Thanks in advance for all your help
Gabe
#643 of 767
Re: Calculated vs Car figures [jana6] by cdhc
Oct 31, 2008 (6:56 pm)
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Replying to: jana6 (Oct 30, 2008 4:41 pm)

I don't ever glide. I always coast in order to charge the battery. I want that battery charging every possible moment. I'm finding that more & more I'm able to keep the battery indicator in the upper light green that I used to. Yes, the green is more fully charged than the blue. The stronger your battery is charged, the easier it is at takeoff for you to start rolling solely on electrical power.
#644 of 767
Re: Calculated vs Car figures [cdhc] by jana6
Oct 31, 2008 (7:08 pm)
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Replying to: cdhc (Oct 31, 2008 6:56 pm)

That's what I do too. That's why I couldn't understand why it says gliding is better but they were talking about gas mileage. Could we possibly get better gas mileage when there is no friction on the engine as there is when coasting? At least that's how I'm interpreting what they are talking about. I would assume it's a trade off that possibly results in better gas mileage but less battery charge. Curious... Any ideas?
#645 of 767
Re: Calculated vs Car figures [cdhc] by prius2007
Nov 01, 2008 (1:49 am)
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Replying to: cdhc (Oct 31, 2008 6:56 pm)

Hi cdhc,
 
Your advice is good in fact I do the same, but if you listen to the experts / people with more experience with the Prius they will tell you this:
There is an energy conversion loss (gas to electric or electric to kinetic). Guess well all the stored battery energy comes from - yes your gas engine. Initially it had to come from the battery and any replenisment has to come from the battery. They recommend to stay off the battery and that a no arrows glide is better than running off the battery. Like you, I also coast (blue arrows only going to the battery) when approaching a red light / stop sign. I've been doing more gliding (no arrows) as a result whenver possible, but since I don't want to hold up traffic I do also run on the battery often.
 
Good luck sounds like you're doing well
Gabe
#646 of 767
Re: Calculated vs Car figures [jana6] by prius2007
Nov 01, 2008 (1:53 am)
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Replying to: jana6 (Oct 31, 2008 7:08 pm)

Hi jana6,
 
You hit the nail right on the head - the claim is that there is no friction when gliding. BTW the Prius MFD is great in showing instant MPG but it only goes to 99.9. I recently bought a Scangauge which goes up to 9999 MPG and even better if you switch it to L/100KM a zero reading means there is not even a trickle of gas is being used when gliding.
 
Best of luck , sounds like you got the bulk of the concept and you can put it into practice,
Gabe

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