Qs: Maintenance while driving little; declining gas mileage

Discussion in 'Gen 4 Prius Main Forum' started by mudworm, Jan 10, 2022.

  1. mudworm

    mudworm Member

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    I have attached a chart of my gas mileage and odometer history of my 2018 Prius II since day one. I log every gas fill. In March 2020, I moved out of the hills, so my commute would have changed from 50 round trip daily on mostly uninterrupted mountain roads to 8 miles daily on city streets, but Covid shutdown started at the same time, so I've been working from home since. There was a time, I barely moved my car. There was a time, I drove two hours on weekends for outdoor trips. But currently, my driving was mostly just very short, but daily, trips to my local gym. I have a few questions:

    1. I don't drive enough to hit the mileage for the scheduled maintenance, should I still take the car in every 6 months to get maintenance (mostly synthetic oil change). (Last service was on 4/23/2021 at 45457; and currently, I'm at 48753.)
    2. My gas mileage has declined from the early days' 50+ MPG to todays 40, and this is comparing winter driving months only (with heater on). Currently, All my short drives are city roads (with some steep hills though). Are there things I can do/check to improve my gas mileage, or is this kind of deterioration full expected?
    3. I just had a new set of tires installed. Was told by the Costco Tire Center that an alignment will be good. For how little/short I drive, is this necessary? I want to do what's best, but only if necessary, for my car.

    I always found this forum helpful, so I hope to hear some good insights and advice. Thanks!
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  2. Mendel Leisk

    Mendel Leisk Sand Pounder

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    1. Toyota says to do the maintenance at the miles or months, whichever comes first. This kinda falls apart if your car is practically mothballed, but with your miles I wouldn't say you're there; I would play by the rules.

    2. Consolidate trips wherever possible. Also, if it's a toss-up: say shopping at a local store, vs driving to a mall, go with the first whenever practical. Give your local merchants some business. These two tactics likely mean the car sitting even more, and it's worth considering a auxiliary charging system for the 12 volt battery.

    3. Unless you're noticing something odd with the steering, recently hit a curb hard, uneven tread wear, something like that, I'd leave it be.

    This is our scenario in spades btw: last time we drove was Monday a week back, fridge and cupboards are well stocked, and the car's sitting on a charger. :)
     
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  3. bisco

    bisco cookie crumbler

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    once a year oil change is fine

    new tires reduce mpg's until they are broken in, unless they are not LRR and rated for the same mpg as the ones replaced.
    alignment is only necessary if the car is not tracking straight, or the old tires wore unevenly.
    winter gas will effect mpg in california.
    as mendel stated, short trips will kill you, and time between drives can deplete the 12 volt battery, then the engine has to run to top it up.
    make sure the new tires are properly pressurized, and check/clean/replace the air filter
     
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  4. TheLastMojojomo

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    I've noticed in my Gen 2 Prius if I don't get a good long freeway trip with cruise control on every once in awhile, gas mileage will slowly decline.

    Try and get a 30 minute+ freeway trip in at 60-70+ mph and see if your mpg improves after that.

    Posted via the PriusChat mobile app.
     
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  5. FuelMiser

    FuelMiser Senior Member

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    Short city drives involving hills will definitely reduce your average MPG. Cold weather/heater needs also take a toll. I see 10 MPG drop typically between summer and winter conditions. The reduction you're seeing, in the 40's now, makes sense given your changed driving conditions. New tires can also reduce your MPG, especially if not "eco/green" low rolling resistance type.
     
  6. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Our 2010 has the block heater, and we try to plug it in 2 hours before any cold start. This helps a bit with the short trip mpg, and I think it's beneficial for engine "well being" too.
     
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