My 2008 has always had better mpg on highway than city, is that a sign of something wrong?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MiaTwo, Feb 22, 2020.

  1. MiaTwo

    MiaTwo New Member

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    I bought my 2008 for a really good deal, and multiple mechanics (Including one who specialized in hybrids) have looked at it and said it was fine after glancing at it for 30 seconds. One of the reasons I thought there was something wrong is that the engine makes a very loud buzzing sound. Everyone says that's just how a Prius sounds, but it's MUCH louder than a normal car when idling. Is that how it's supposed to be?

    Another reason I suspect a problem is I get exactly 38mpg when driving in the city. Granted I don't try to hyper-mile, that's just with regular, average driving. I usually get closer to 50-60 mpg when driving on the highway, though lately it's seemed a little lower (About 48 during my last trip).

    I changed the cabin air filter, should I change the other one too? Or does anyone have an idea what I should try? Or is that completely normal? The internet says I should be getting better mileage in city than highway? Or is that just with strategic driving?
     
  2. SFO

    SFO Senior Member

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    Should I ask how many miles you have on the vehicle, or how you're measuring the MPG?
     
  3. egg_salad

    egg_salad Active Member

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    I likewise live in LV and drive an '08. 38 is significantly lower than what I see. Are you doing a lot of short hops? Any journey of under about 10-15 miles is sub-optimal for fuel economy.
     
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  4. edthefox5

    edthefox5 Senior Member

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    Where on the internet do you see a Prius g2 is supposed to get better mileage in the city? Show me.
    a G2 Prius gets the best mileage on the highway stop and go will kill mileage.

    It’s not a Prius C.

    Any degradation in mileage is usually because the hybrid battery is getting old and does not produce the power it used to so you push on the gas pedal more to achieve the speed and power you are used too.

    Your battery is 11 years old.

    The majority of 2007 Prius are now experiencing battery issues soon to be the majority of 2008s.

    Use the search forums tab up top and search

    Hybrid battery

    To see what we are all going through,
     
  5. fuzzy1

    fuzzy1 Senior Member

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    That is an artifact of the EPA rating scale, which applies different artificial fudge factors to the separate Highway and City test cycles. And very few people have drive patterns that make either test cycle.

    YMMV (Your mileage may vary), and your HIghway and City mileage may vary quite differently. Some people actually do get better city mpg, but many others get better on the highway. In itself, this is nothing to worry about.

    Separately, your city mpg seems low. Are your city trip lengths short? Since your highway mpg appears good, it suggests that the car is fine, that the 'problem' is a short or mpg-unfriendly route.
     
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  6. pasadena_commut

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    Warm up time, trip length, and ambient temperature are key determinants of city MPG.

    If the car gets very cold (like parked outside overnight in the desert that is LV) then it will take around 5 miles before it fully warms up. That is a rough estimate based on it taking about 2-3 miles in SoCal with not quite so cold nights.

    I typically drive 7.5 mile trips twice a day and our 2007 gets ~47 MPG when it is nice (70F-80F), ~45 MPG when it is a little chilly (60F), and ~43 MPG on (for us) cold days of 50F. These numbers are based on the trip MPG display. It takes a month for this car to use up a tank so MPG calculated that way is integrated over all sorts of temperatures and not very informative.

    If you don't mind wasting a little gas, just do the experiment. Start up the car as you normally would and drive it normally, but keep on driving. Check the estimated MPG at 1, 2, 3, 4, 5, 10, and 15 miles. Better yet, have a passenger do it. You should find the MPG shown starts low and then eventually flattens out once the low MPG at the beginning becomes a small fraction of total miles driven in that trip. The bar graph will show some of that but it has a 5 minute resolution so it won't be informative for the first four minutes.
     
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