1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Just a couple of newbie questions

Discussion in 'Newbie Forum' started by Robert Chen, Jul 8, 2012.

  1. Robert Chen

    Robert Chen Junior Member

    Joined:
    Jul 8, 2012
    5
    0
    0
    Vehicle:
    2002 Prius
    Model:
    N/A
    1. I know that there's a discrepancy between the car displayed mpg and hand calculated mpg. Here's my situation. First full tank I drove until completely empty pretty much, and the displayed value was around 47 and my calculate value was around 48, this was mostly city driving. Later on, because I didnt get a chance to drove until the tank was completely empty, sometimes I filled up at half, sometimes with 3 bars left, etc, I found that there's a really really huge discrepancy, like the time I had 3 bars-ish left, the displayed mpg was 45+ and the calculated mpg was 40ish. Today, I filled up to full on a tank with 5ish bars left, the display, 45, the calculated was 38... What's going on here?

    2. Is the battery display actually show how full the battery is?

    3. Is there another battery for longer term energy storage or is there only 1 battery?

    4. Oil change often? Or it doesnt really matter?

    5. change tires? My tires are really really worn out, lol... would changing them improve mpg?

    6. tire pressure, how much?

    7. Am I supposed to drove from full to completely empty or more than completely empty? Or does that not matter?
     
    #1 Robert Chen, Jul 8, 2012
  2. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,123
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    Welcome aboard!

    Is your user info correct? You have an 02 Prius?

    2) For 2nd gens (04-09), someone did this: Prius Palm Mileage Simulator.

    3) There's a large HV battery and there's a small 12 volt as well. It should be described in your manual. There's some more info at TIS.

    4) See your maintenance booklet.

    5) Maybe. What's the make, model and size on there now? Tire Information for the Prius: LRR and Tire Tests | PriusChat might help

    6) It would help to tell confirm which model year you have first.

    7) ??? Full what? Empty what?
     
    #2 cwerdna, Jul 8, 2012
  3. richard schumacher

    richard schumacher shortbus driver

    Joined:
    Mar 27, 2004
    7,663
    1,038
    0
    Location:
    United States
    Vehicle:
    2004 Prius
    Model:
    N/A
    I'm guessing that you don't have a copy of the Owner's Manual for your model and year? If not then buy one, either online or from a Toyota dealer. It's full of info you need to know.

    And if you don't have the Owner's Manual you probably don't have the Maintenance Guide either. For Toyota's recommended maintenance schedule see here:
    Toyota Parts and Service
     
    #3 richard schumacher, Jul 8, 2012
  4. Robert Chen

    Robert Chen Junior Member

    Joined:
    Jul 8, 2012
    5
    0
    0
    Vehicle:
    2002 Prius
    Model:
    N/A
    Yes, it's a 2002 prius, so Gen I. I still dont understand why there's such a huge discrepancy between the calculated value and the displayed value.

    I was saying am I supposed to drive the car from a full tank of gas to over an empty tank of gas to get better mpg? cus like I said, that one time when I did that, I got much better mpg, and later on I just havent gotten a chance to drive the car from full to empty.

    I have the Owner's manual, I dont know about the maintenance guide... I'm a bit confused about what the website is saying, the car has so and so miles on it, I dont know when was the last time the car had a oil change and whatnot.

    Okay, and I'm guessing on the energy display, the battery picture that shows how full the battery is the HV battery. I just wanna know if there's electric energy stored somewhere else on the car, because like I said, that one time when I drove the car from full tank to empty, it felt like it was draining energy from somewhere, cus the tank was pretty much empty, and the HV? battery can only provide so much electric energy.
     
    #4 Robert Chen, Jul 8, 2012
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,679
    48,931
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    no, driving from a full tank to empty won't improve your mileage. single fill up calculations are not as accurate as averaging over several tanks because there is no way to know how full the tank is each time you fill up. the hv battery is the only one that stores motive energy and the differences you are seeing in mpg's is likely more closely related to driving style, route type (traffic, hills, speed, etc.) and outside temps.
     
    #5 bisco, Jul 8, 2012
  6. Robert Chen

    Robert Chen Junior Member

    Joined:
    Jul 8, 2012
    5
    0
    0
    Vehicle:
    2002 Prius
    Model:
    N/A
    thanks yall for the answers. Sorry about the whole discrepancy issue, I guess I wouldnt be so concerned if the discrepancy was always in the negative, like when it says 45, it really means like 40, I can understand that, just that one time the display was 46 and I got 48. It's just really puzzling.

    I saw that people are DIY converting their non plug in hybrid into a plug in hybrid. Should I do something similar? If so, where can I find a guide and whatnot on the subject?

    From what I can see, here's a couple habits that I should do, correct me if I'm wrong.

    1. If at full stop, I should accelerate quickly to get to what speed I want to be.
    2. Then Glide or Coast, try not to brake at all
    3. switch to neutral at red lights

    Thanks again everyone.
     
    #6 Robert Chen, Jul 8, 2012
  7. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,679
    48,931
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    1&2) accellerate smartly but don't gun it. get it up to a little faster than you want to go so you can glide longer before having to accellerate again and let it drop to a few mph below your target before gassing it again. but don't drive the people behind you crazy.:)
    3) no need to switch to neutral.
    search for plug in threads using different terms, there are tons of them. you can also find them easily scrolling thru 'what's new'.
     
    #7 bisco, Jul 8, 2012
  8. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,123
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    You can get a copy of that at Toyota Online Owners Manuals and Technical Manuals. Select the proper car and year in the upper right.

    How many miles are on it?
     
    #8 cwerdna, Jul 8, 2012
  9. User37

    User37 Can spell PRIUS

    Joined:
    Sep 13, 2009
    83
    14
    1
    Location:
    Italy
    Vehicle:
    2010 Prius
    Model:
    N/A
    There are two philosophies with respect to calculating the mpg. Some drive the tank to empty then refill.
    Their reference is the "empty" mark on the gas gage. The amount refilled is the consumed part. Not all gas gages are accurate and few are linear so there will be an inaccuracy. (Actually the gas gage is one of the most complained item in all car related forums, independent of brand or make)

    The other method is to refill the tank completely, on a flat surface until the pump automatic switches off first time. Pumps tend to be very accurate (due to laws and stuff ;) ) Again the amount refilled is the consumed volume, but this method tends to be more accurate. Also there is no need to wait for the tank gage to show empty.
     
    #9 User37, Jul 9, 2012
  10. Robert Chen

    Robert Chen Junior Member

    Joined:
    Jul 8, 2012
    5
    0
    0
    Vehicle:
    2002 Prius
    Model:
    N/A
    Thanks yall, crisis averted, I just had to pump the tire up to the right pressure.
     
    #10 Robert Chen, Jul 26, 2012
(You must log in or sign up to post here.)