Dropping MPGs on 2010 III

Discussion in 'Newbie Forum' started by Laura R, Jul 24, 2010.

  1. Laura R

    Laura R New Member

    Joined:
    Jul 24, 2010
    4
    0
    0
    Location:
    california
    Vehicle:
    2010 Prius
    Model:
    III
    I have a 2010 III which is now 8 months old. In the beginning I was getting around 47 mpg around town. Lately it has dropped to around 37 mpg. I live in a very hot area and I run the a/c most of the time. No other problems and nothing new has been added. Any ideas?
    thanks, Laura
     
  2. ksstathead

    ksstathead Active Member

    Joined:
    May 1, 2007
    1,244
    242
    0
    Location:
    Kansas
    Vehicle:
    2010 Prius
    Model:
    III
    Yes, I have some thoughts. By the way, my III is one month newer than yours, so I'll be curious what you find in case the same happens to me.

    1. Reset trip B, turn off the AC, roll down driver and rear passenger windows a little, go for a typical drive and see what the mpg does. Granted, it may need to be early morning or at night. I would definitely find out if AC is the cause. If mpg ok on this test, then run the same test with your usual AC setting for comparison.

    or 2. What setting do you have the AC on? Set the temp higher than normal, as high as you can take, and see if mpg improves.

    or 3. What changed coincident with the drop? Was that when it got so hot?

    4. Do you know anyone with a scangauge? This can be very useful in watching various temps, rpms, etc.

    5. Have you had the oil changed? Often dealers and others overfill which can hurt mpgs. Check the oil. It should not be over the full mark.

    6. How many miles on the clock?

    7. Check and report tire pressure. Should be minimum of the pressures on the door placard; better more toward maximum sidewall rating, say 44 front/42 rear. The tpms is not very sensitive, so you could be very low without getting a warning light.

    That's all I can think of right now.
     
    1 person likes this.
  3. kazak

    kazak New Member

    Joined:
    Jul 19, 2010
    21
    2
    0
    Location:
    Austin
    Vehicle:
    2010 Prius
    Model:
    III
    Not to hijack this thread but a question....

    So how does the AC affect mpg? Is the the lower the temp or the higher the fan speed?
     
  4. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,117
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    Please answer most of the questions at http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html. That would give us a lot more to go on.
     
    1 person likes this.
  5. ksstathead

    ksstathead Active Member

    Joined:
    May 1, 2007
    1,244
    242
    0
    Location:
    Kansas
    Vehicle:
    2010 Prius
    Model:
    III
    Heat exchange is the bigger drain versus fan speed, but both use power from the gas tank.
     
  6. Laura R

    Laura R New Member

    Joined:
    Jul 24, 2010
    4
    0
    0
    Location:
    california
    Vehicle:
    2010 Prius
    Model:
    III
    So today it's a little cooler than it has been and this morning I drove around a bit with no a/c. I got 41 mpg.
    I have not yet had the oil changed as the dealer told me I didn't need to until I hit 10,000 miles. I am currently at 8400 but I think I might have it changed anyway. I did check it and it looked a little low although I'm not sure on the reading.
    My next step is to check the tire pressure and adjust if necessary.
    The only change I can think of would be the temp. We have recently seen high 90s and low 100s. Most of my driving has been short trips with lots of stops and gos. I drive it mostly in the 'normal' mode. (not ECO or Power or EV)
    I'm not obsessed with my mpg but I would like to see enough of a difference to justify the money I spent on the car.
    Laura
     
  7. rlr66

    rlr66 Junior Member

    Joined:
    Mar 21, 2009
    88
    8
    0
    Location:
    Long Island, NY
    Vehicle:
    2010 Prius
    Model:
    IV
    I would think the tire pressure has a lot to do with it. Check that and see the difference especially with the weather getting so hot the tires tend to grip the road more when the pressure is low.
     
    1 person likes this.
  8. ksstathead

    ksstathead Active Member

    Joined:
    May 1, 2007
    1,244
    242
    0
    Location:
    Kansas
    Vehicle:
    2010 Prius
    Model:
    III
    Laura, something is wrong. Once found, the car should at least do what it did at first. Should do better as you learn to exploit its potential and as it breaks in.

    Tire pressure, a dirty MAF sensor, a fouled spark plug. I don't know what, but I would bet an experienced mechanic can find it, no hybrid experience is needed (my guess).
     
    1 person likes this.
  9. spiderman

    spiderman wretched

    Joined:
    Jul 5, 2009
    7,543
    1,540
    0
    Location:
    Alaska
    Vehicle:
    2010 Prius
    Model:
    II
    Could you describe your typical commute/drive in detail (distance, speed, and elevation change if you have that)? Short trips are a FE killer.
    Totally understand wanting to get at least close to the EPA ratings!
     
    1 person likes this.
  10. Laura R

    Laura R New Member

    Joined:
    Jul 24, 2010
    4
    0
    0
    Location:
    california
    Vehicle:
    2010 Prius
    Model:
    III
    Typically I drive 10-15 miles. Level roads, low elevation, suburban area. Average speed is around 40 mph but many stop lights. As mentioned earlier, it has been 100+ degrees for about 2 weeks. The drop in mpg started about 5 weeks ago. It was in the 90s then. I run the a/c almost all the time and set it at 73 degrees.
    In the 9 months that I have had the car, the highest mpg was 51 and that was on a long trip with some down-hill stretches.
    thanks to all
     
  11. Colonel Ronson

    Colonel Ronson New Member

    Joined:
    Jul 11, 2010
    443
    33
    0
    Location:
    Tucson, AZ
    Vehicle:
    2010 Prius
    Model:
    II
    what you are experiencing shouldn't be normal. i run the a/c full blast on auto all the time, and i still avg 50 mpg. It could be our tires. It could be a clogged air filter, hell it could be a faulty battery.

    It could also be your brand of gasoline. What are you filling? have you tried something different?
     
    1 person likes this.
  12. spiderman

    spiderman wretched

    Joined:
    Jul 5, 2009
    7,543
    1,540
    0
    Location:
    Alaska
    Vehicle:
    2010 Prius
    Model:
    II
    Is that continous or do you make many stops (park, turn off car)? Seems like what you have describe, you should be getting in the 60+ range like Mark57. I am thinking something is wrong with the car too.
     
    1 person likes this.
  13. Laura R

    Laura R New Member

    Joined:
    Jul 24, 2010
    4
    0
    0
    Location:
    california
    Vehicle:
    2010 Prius
    Model:
    III
    I fill-up with gas at CostCo. Have no idea where they get their gas.
     
  14. JimN

    JimN Let the games begin!

    Joined:
    Nov 26, 2006
    7,028
    1,113
    0
    Location:
    South Jersey
    Vehicle:
    2010 Prius
    Model:
    V
    Laura, regardless of where you are or how you drive expect to get ~25mpg over the 1st 5 minutes because the ICE runs just to get warm. Operating temp is ~190F. The 2nd 5 minutes of continuous driving can start delivering 50mpg.

    Turning the car off also drops the FE as the heating process restarts. When outside temps are moderate I leave the car on & locked (manually) for quick trips of 5-10 minutes. If the OAT is in the 90's F leaving the car sit will drop the battery's SOC.

    Can you up the temp on the AC? 73 sounds cold. My car sits outside all day with the windows up & we've had more than our share of 90+ days. I keep the AC at 78-79 with the fan speed at 1-3 bars.

    I really suspect your tp. IMO the pressure on the door is very low. Read the tire's sidewall. At that pressure you'll get longer tire life & better handling.

    Since the oil is within the 2 marks on the dipstick it isn't overfilled so that shouldn't be a cause.

    Do you coast up to red lights or race up to brake to a stop? Accelerating & braking at lights isn't efficient. Can you reduce your speed to minimize the braking?

    I dare say that for many of us if we kept the car at the stock configuration we wouldn't be getting the FE we do.
     
Loading...