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Toyota Prius MPG-Real World Numbers

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

You are in the Toyota Prius Forum. Your Host is pf_flyer

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


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#647 of 767
Re: Calculated vs Car figures [prius2007] by kdhspyder
Nov 01, 2008 (5:32 am)
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Replying to: prius2007 (Oct 31, 2008 5:32 am)

Nice job! 27000 mi / 455 gal = 59 mpg.
 
You obviously got the secret Super Ultra Efficiency option package that very few knew about and which allows you to be in the upper 1% of all Prius owners. I didn't know the code for that option or I would have chosen it also.
 
For the rest of us plebians we have to make do with just good normal results. Nice hand, sir.
#648 of 767
Re: Calculated vs Car figures [jana6] by cdhc
Nov 01, 2008 (7:30 am)
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Replying to: jana6 (Oct 31, 2008 7:08 pm)

I do have a background on the subject of regenerative braking, kinetic energy, etc. For a living I engineer & sell industrial machinery, and regen braking is nothing new. Its just new to the consumer market. The primary source of energy in the Prius is, yes, the gas tank. One thing about the engineering that went into designing the Prius is that it utilizes every opportunity to capitalize on motion being used to charge the battery. On a car that has conventional brakes, during the action of braking, heat is generated. This heat is a direct representation of energy that is lost. In regen braking, the energy is captured from the momentum of the wheels, and this energy is used to back-drive the electric motor, thus charging the battery. Its important to brake lightly. If you use a heavy brake, the brake pads kick in to stop the car, and energy can be lost due to heat being generated.
 
When you are driving, and you take your foot off the accelerator (coasting), the car then uses the momentum of the wheels to back-drive the electric motor, thus charging the battery. This method of charging is much more efficient than regen braking since there will not be as much energy lost due to heat being generated.
 
Its true that gliding can help you go a little further than coasting, but gliding does nothing at all to charge the battery. What may be perceived as friction while coasting is actually the electric motor being back-driven. And yes, with any rotating part, there is friction. That's just something that cannot be avoided. You even have friction in the wheel bearings while simply gliding.
 
I don't know. There's people that get better gas mileage than me, but I'm happy with my average of 57.5.
#649 of 767
Re: Calculated vs Car figures [prius2007] by cdhc
Nov 01, 2008 (7:31 am)
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Replying to: prius2007 (Nov 01, 2008 1:49 am)

I do have a background on the subject of regenerative braking, kinetic energy, etc. For a living I engineer & sell industrial machinery, and regen braking is nothing new. Its just new to the consumer market. The primary source of energy in the Prius is, yes, the gas tank. One thing about the engineering that went into designing the Prius is that it utilizes every opportunity to capitalize on motion being used to charge the battery. On a car that has conventional brakes, during the action of braking, heat is generated. This heat is a direct representation of energy that is lost. In regen braking, the energy is captured from the momentum of the wheels, and this energy is used to back-drive the electric motor, thus charging the battery. Its important to brake lightly. If you use a heavy brake, the brake pads kick in to stop the car, and energy can be lost due to heat being generated.
 
When you are driving, and you take your foot off the accelerator (coasting), the car then uses the momentum of the wheels to back-drive the electric motor, thus charging the battery. This method of charging is much more efficient than regen braking since there will not be as much energy lost due to heat being generated.
 
Its true that gliding can help you go a little further than coasting, but gliding does nothing at all to charge the battery. What may be perceived as friction while coasting is actually the electric motor being back-driven. And yes, with any rotating part, there is friction. That's just something that cannot be avoided. You even have friction in the wheel bearings while simply gliding.
 
I don't know. There's people that get better gas mileage than me, but I'm happy with my average of 57.5.
#650 of 767
Re: Calculated vs Car figures [cdhc] by jana6
Nov 01, 2008 (5:38 pm)
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Replying to: cdhc (Nov 01, 2008 7:30 am)

This does make sense. Thanks. (And I have no engineering background so thank you for putting it in terms I understand!) I do wish I could get 57.5 mpg but I guess it just isn't in the cards for me. My 15-20 minute drive to work is 1/2 city, 1/2 highway. If I would get up early enough to leave early, I could go all city and do better there but.... Also, even though I plan my short trips in clumps, it just isn't that easy to avoid the 5 minute drives from here to there. But at least I now understand why I'm not getting the mileage and am willing to accept it. I do appreciate all of you for all your help.-
#651 of 767
Re: Calculated vs Car figures [prius2007] by jana6
Nov 01, 2008 (5:48 pm)
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Replying to: prius2007 (Nov 01, 2008 1:53 am)

Hi Gabe,
 
The Scangauge sounds interesting. Where would one get it, is it hard to install, and where does the unit sit int he car?
 
Thanks for all your help and advice. I loved my Prius even with the lower mpg than I was expecting but now I love it even more knowing the reasons why I'm not getting that mpg. I'm working more on all the suggestions and this tank is showing 50 mpg. That makes me very happy.
 
Thanks again,
Jana
#652 of 767
Re: Calculated vs Car figures [jana6] by prius2007
Nov 02, 2008 (4:01 am)
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Replying to: jana6 (Nov 01, 2008 5:48 pm)

Hi Jana,
 
I was just reading this tread over on PriusChat on SGII:
link title
you can also use their search function. Also on www.cleanmpg.com you'll find lots of good info on the subject. Both sites at times have a group buy or discounted price on the SGII and advertise it on the site or look in the PriusChat shop. I think the price is already discounted. The manufacturer's website is: link title
 
One reason I got it is to monitor my water temp to feel safer when using grill block. You can also get segment MPG numbers. BTW congrats on your great MPG (WOW you got to 50) with your short trips and all. You're another proof that if people are interested it is possible despite of all the nay sayers. I'm going to read some of your prior posts to get more details of your driving profile and if possible offer you some additional tips. You got some good ones already from cdhc he knows what he is talking about
 
Best of luck,
Gabe
#653 of 767
Re: Calculated vs Car figures [jana6] by prius2007
Nov 02, 2008 (4:21 am)
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Replying to: jana6 (Nov 01, 2008 5:48 pm)

Hi Jana,
 
For (especially) short trips an engine block heater (EBH) helps. It will improve warm up time thus the first 5 minutes MPG. This is especially useful in colder weather. They can be put on a timer an kick in say 3 hours before taking off. In colder weather lot of us use grill blocking partial to full pending how cold it is. Also have you looked in tire pressure you may want to consider it. You already talked about combining short trips - that's great too.
 
link title has many other great info - there is a Fuel Economy forum. Good luck,
Gabe
#654 of 767
Re: Calculated vs Car figures [prius2007] by jana6
Nov 02, 2008 (5:37 pm)
Reply

Replying to: prius2007 (Nov 02, 2008 4:01 am)

Hi Gabe,
 
Great! I've checked them out and have put both in my favorites. I'll have my mechanic friend check it all out for me for further guidance on the SGII.
 
When I filled up today (less than 5 gallons actually), the actual came up to 56.57 so I probably didn't fill it up all the way because of the bladder but that sure was nice to see (the computer still said 50 which I'm happy with). Next fill up should give me a better idea of the real numbers.
 
I live in Las Vegas so the summer heat does affect the gas mileage--sorry, must use AC! The winters are very mild but the evenings can get down into the upper 30's (usually more like the 40's though) and the days range from the 40's to the 60's. I can't say I noticed any better or worse gas mileage last winter but am now keeping track of it all so I'll have a better handle on the numbers.
 
I'm going to get my oil changed tomorrow morning and will have them put the back tire air pressure at 40 and the front at 42. At least I think that's what it said to do. I'll double check that. I think it said the front should be 2 lbs higher than back.
 
Again, thanks for all your help.
#655 of 767
Re: Calculated vs Car figures [jana6] by cdhc
Nov 07, 2008 (12:12 pm)
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Replying to: jana6 (Nov 01, 2008 5:48 pm)

I was so elated today when I gassed up, I just wanted to share with you and everyone. I've put into hard use the 2 most recent tips I've learned about tire pressure, and not driving over 57mph. I knew this tank was good when I went over 350 miles, and the gas gauge barely hit the halfway mark. The computer showed 59.3mpg. After filling up (and yes I do top-off), it revealed 62.3mpg actual. Last week was 57.7mpg. I hope your mileage is improving. Yippppeeee ! ! ! ! !
#656 of 767
Re: Calculated vs Car figures [cdhc] by pf_flyer HOST
Nov 07, 2008 (3:40 pm)
Reply

Replying to: cdhc (Nov 07, 2008 12:12 pm)

Woo woo...
 
Keep up those good habits!

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