Sudden Drop in Fuel Economy After Service - Ethanol additive in fuel?????

Discussion in 'Gen 2 Prius Fuel Economy' started by nick63, May 24, 2006.

  1. nick63

    nick63 New Member

    Joined:
    May 24, 2006
    4
    0
    0
    I have a 2004 Prius with 17,000 miles on it. I live in S. California. My average mpg has generally been around 43-44mpg (I live in the hills). Last week, I had an intermediate service, and after getting the car back, am now running at approx a crappy 36mpg. And that's with new tires and realignment.

    So I took the car back today to the service station in Santa Monica and had them run tests and re-check. They found nothing wrong with the car that would explain the sudden drop.

    They did say that they checked nine Prius' on the lot and the average on them at the moment was approx 38.5. And that some owners had been recently complaining of a fuel economy drop.

    They suggested that the drop was due to one of two things -
    1) Air conditioning - which they said can cause a 5mpg drop, except I rarely use it, so it's not that.

    2) The summer addition of ethanol in the gasoline which apparently reduces fuel economy in all cars.

    So my questions are -

    Has anyone else heard of that problem, has anyone else had a sudden drop in fuel economy, and after a service??

    thanks

    Nick
     
  2. IsrAmeriPrius

    IsrAmeriPrius Progressive Member

    Joined:
    May 27, 2004
    4,333
    6
    0
    Location:
    Southern California
    Vehicle:
    2005 Prius
    <div class='quotetop'>QUOTE(nick63 @ May 24 2006, 08:48 PM) [snapback]260736[/snapback]</div>
    Nothing this drastic. Did you check the viscosity of the oil that they put in the crankcase and the oil level?
     
  3. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,188
    4,866
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    <div class='quotetop'>QUOTE(nick63 @ May 24 2006, 10:48 PM) [snapback]260736[/snapback]</div>
    Until they wear down a little, MPG will be lower. I've witnessed that effect several times now.

    Low pressure in the tires has a noticeable MPG influence too.

    As for ethanol, my lifetime average is 48.5 MPG using a 10% ethanol blend all 54,000 miles (2.5 years).
     
  4. mgmb

    mgmb Junior Member

    Joined:
    Feb 21, 2006
    17
    2
    0
    I just had my 5K service done on my 2006 and have noticed that my mpg has also drop alittle from 45 to 43.
     
  5. nick63

    nick63 New Member

    Joined:
    May 24, 2006
    4
    0
    0
     
  6. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,188
    4,866
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    The tiny edges of tread on new tires, which add up to a surprising amount of gripping area, are very sharp.

    Take a good look (extreme close-up photo would be great) at them now, then 1000 miles later. You'll notice a correlation between the tiny wear and the MPG improvement.
     
  7. nick63

    nick63 New Member

    Joined:
    May 24, 2006
    4
    0
    0
    <div class='quotetop'>QUOTE(john1701a @ May 24 2006, 09:01 PM) [snapback]260764[/snapback]</div>
    Very interesting that new tires could be a negative influence on fuel economy, but could that account for a such an abruptly precipitous drop from 44 to 36 mpg?

    And do you know anything about the ethanol mixture in the summer stock of fuel affecting fuel economy for the worse?

    thanks.
     
  8. tomdeimos

    tomdeimos New Member

    Joined:
    Feb 16, 2004
    995
    2
    0
    Location:
    Lexington, MA
    Ethanol fuel costs me about 3 mpg.
     
  9. hycamguy07

    hycamguy07 New Member

    Joined:
    Feb 18, 2006
    2,707
    2
    0
    Location:
    Central Florida
    Vehicle:
    2007 Prius
    1) Air conditioning - which they said can cause a 5mpg drop, except I rarely use it, so it's not that.

    :huh: The A/C isnt connected to the motor its electric... I could see this on a standard A/C unit on a non-hybrid vehicle...

    The mileage drop wouldnt be that much on a Hybrid... :rolleyes:
     
  10. Tadashi

    Tadashi Member

    Joined:
    Feb 25, 2005
    796
    4
    0
    Location:
    Fort Hood, TX
    Vehicle:
    2005 Prius
    Model:
    N/A
    Check your tire pressure. The same thing happened to me and I found out they reduced my tire pressure from 42 psi to 35 psi. This cost me about 8 mpg. Once I put it back up everything was back to normal. I now tell them nto to mess with the tire pressure.
     
  11. nick63

    nick63 New Member

    Joined:
    May 24, 2006
    4
    0
    0
    <div class='quotetop'>QUOTE(Tadashi @ May 25 2006, 08:10 AM) [snapback]260911[/snapback]</div>
    42 psi? Won't that be too much and shoot your tires after a while? Mine are currently set at 32psi by the Toyota mechanics at the service. I shall definitely put up to 35, but 42??
     
  12. vikingrob

    vikingrob New Member

    Joined:
    Mar 24, 2006
    37
    0
    0
    Location:
    Minneapolis, MN
    Ethanol contains less energy per gallon than gasoline, but I don't see how going from no ethanol to about 10% would produce that big of a drop. Something else is in play here. Even if ethanol contained zero energy content, a 10% ethanol concentration would only account for roughly half the drop.

    <div class='quotetop'>QUOTE(nick63 @ May 25 2006, 12:06 AM) [snapback]260765[/snapback]</div>
     
  13. richard schumacher

    richard schumacher shortbus driver

    Joined:
    Mar 27, 2004
    7,656
    1,012
    0
    Location:
    United States
    Vehicle:
    2004 Prius
    Model:
    N/A
    <div class='quotetop'>QUOTE(nick63 @ May 25 2006, 11:21 AM) [snapback]260915[/snapback]</div>
    It's completely safe for the original tires (Goodyear Integras), which are rated at 44 PSI. (Tire pressure is checked "cold", which means that the car has not been driven more than one mile in the past hour.) Lower pressures are a compromise between fuel economy, handling, and ride. I've used 42/40 for two years with no trouble. The ride is harsher and the handling is different, so if you do try higher pressures pay attention.
     
  14. HybridVigor

    HybridVigor New Member

    Joined:
    Jul 24, 2005
    96
    0
    0
    Location:
    Chandler, AZ
    <div class='quotetop'>QUOTE(richard schumacher @ Jun 8 2006, 07:13 AM) [snapback]267871[/snapback]</div>
    I had a similar experience with my first Toyota service at 5000 miles - mileage dropping. Interesting thing was that although my MFD mileage dropped, my mileage based on miles/gallons stayed essentially unchanged. I attribute this to three things. 1. Toyota updated my computer's programming without telling me. 2. They rotated my tires causing differing wear which was more apparent in the instantaneous mileage than the final tank mileage. 3. They lowered my tire pressure from 42 to 32 psi.
    Out of all of these, the only one I'm annoyed about was the computer upgrade, really. I understand that they are required by Toyota to set tire pressure to "specs." I have an air compressor at home, so I quickly remedied that problem. I recommend re-pressurizing your tires, and then waiting it out to see what happens. Temperature changes affect this car more than any other, and that may also have its pound of flesh, even though you don't recognize it right off. If no A/C, then are you driving with the windows down more than before? That'll affect things. Have you done more driving in hilly areas recently? Just some thoughts.

    --Chris
     
  15. pointreyesman

    pointreyesman New Member

    Joined:
    Aug 10, 2008
    3
    0
    0
    Location:
    northern california
    Vehicle:
    2006 Prius
    I just had four new tires put on my Prius (Michelin Hydro Edge) and the MPG dropped by 20%! Previous MPG average per tank was 45. The new average 36. AND the road noise was similar to running snow tires! Awful tires. Dealer replaced them at no charge with something else by Michelin and the noise is back to normal levels but the milage is still less than old tires (which were Michelin Harmony). Any thoughts? Anyone?
     
  16. pointreyesman

    pointreyesman New Member

    Joined:
    Aug 10, 2008
    3
    0
    0
    Location:
    northern california
    Vehicle:
    2006 Prius
    oh...the tire dealer did a minor 70k service while he was changing the tires. I think it was an oil change, air filter and some fluid checks. He swears it wasn't caused by anything he did.
     
  17. hobba

    hobba New Member

    Joined:
    Jun 25, 2006
    85
    3
    0
    Location:
    Estero, FL
    Vehicle:
    2005 Prius
    I have experienced the same dramatic loss of mileage from 45-50 mpg to 35-40 mpg. Please read the thread I started entitled, "After Service Issues". It gives details of my experience all the way to Toyota's corporate reply to me. I would be happy to answer any questions I can, although I'm still searching for answers myself.
     
    1 person likes this.
  18. galaxee

    galaxee mostly benevolent

    Joined:
    Mar 14, 2005
    9,810
    439
    0
    Location:
    MD
    Vehicle:
    2005 Prius
    tires give worse mpg during break-in. different types of tires have different rolling resistance. lots of factors. give it a couple thousand miles.
     
  19. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,188
    4,866
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    I'm on my second set of HydroEdge tires now. Going from factory-to-them and from the same old-to-new didn't have any more than the usual break-in. 48 MPG remains my average. Mine are not noisy either.

    I bet they sold you an incorrect/larger size. PSI really low in one or more tires would have a big impact too.

    .
     
  20. blamy

    blamy Member

    Joined:
    Sep 18, 2007
    380
    10
    0
    Location:
    Central Florida
    Vehicle:
    2007 Prius
    Florida started adding Ethonal (up to 10%) a couple of months ago and my mileage dropped from 52mpg to 46mpg. It was an immediate drop in mileage so I'm positive it was the Ethanol that caused it. I also got verification from several other Prius owners in the area that there mileage was also suffering.
     
Loading...