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Normal mpg roadtrip

Discussion in 'Gen 3 Prius Main Forum' started by bamajoe, Nov 29, 2018.

  1. bamajoe

    bamajoe New Member

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    Just finished a 4800 mile trip (Mississippi to California and back) with my wife and 10m old son and all necessary luggage. Interstate 40 almost the whole way. Saw a lot of 80mph. Averaged 41.1mpg which seems low to me.. I know that headed west we drove hwy82 the first day at 65mph and averaged 45mpg but that's flat country. Does this seem normal? Havnt had the car long and don't feel like it gets mpg I expected. Although coming from a 13mpg jeep I'm not complaining

    Posted via the PriusChat mobile app.
     
  2. Johnny Cakes

    Johnny Cakes Senior Member

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    I think 41.1 MPG at 80 MPH is excellent.
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    Yes, that is excellent for 80 mph.

    So, what would you think your average speed was? Then look at that speed on this chart:
    Updated MPG vs MPH chart | PriusChat

    Then make some adjustment for winter gas, which always cuts MPG a bit. The total cargo load also causes a bit of drag compared to a solo driver, especially when mountains are added in. Did you run into much wind? Rain?
     
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  4. Raytheeagle

    Raytheeagle Senior Member

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    Here’s the first leg of our trip from Nor Cal to Palm Desert:

    99F8FA6E-3CBA-4FF4-9FA4-7DC087D18014.jpeg

    A little better than you, but within reason given the speed;).
     
  5. kc5dlo

    kc5dlo Active Member

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    The second time I went thru West Texas with the 85 mph speed limit, I resisted the urge to drive up to the speed limit.
     
  6. mysticeyes

    mysticeyes Junior Member

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    80mph and getting over 40mpg all day long, you're doing fine!
     
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  7. FuelMiser

    FuelMiser Senior Member

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    Sustained highway driving does not give the opportunity for brake regeneration to recharge the traction battery, so highway MPG is always going to be lower than city driving. The exact opposite of normal gasoline only cars. Higher speed operation also contributes to more gasoline burned per mile.
     
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  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Note also, OP has a level "5", likely the 17" wheels, which cuts mpg a bit. In the same boat here, ok with it.
     
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  9. ALS

    ALS Active Member

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    Lots of factors affect mileage in a Prius. Weight with passengers and luggage, the 17 inch wheels are good for a 2-3 mpg drop in mileage over the 15 inch wheels.

    Brand of tires are they LRR or regular passenger car tires? Weather, rain no rain, was it cold under 50 or over 75 during your trip, this also affects your mileage.

    As others have said and I agree if you were pushing 80 mph and were getting above 40 mpg I wouldn't complain.

    BTW Perfect conditions I get 56 mpg at 65 mph and 63 mpg at 55 mph. I have no idea what my fuel mileage is above 65 mph because I've never driven the car on a long trip where I exceeded that speed.
     
  10. Sporin

    Sporin Prius Noob

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    Yup. Here in cold, hilly Vermont where we do mostly highway driving (very little stop and go) I've got a lifetime average of about 44 on my 2010. I'm perfectly fine with that. I see a big drop every winter with snow tires, lots of heater use, etc.

    We go to southern Maine regularly and much of that is on gentle secondary roads with a steady 40-50 mph. I've seen long stretches of 55-60 mpg average going that way as the car is really in it's element.

    Longest road trip I've taken the Prius on was VT - NC and back. I got almost exactly 50mpg hand-calculated for that entire trip. Much of it was 75-80mph down I-95. Felt like it was all downhill headed south and uphill headed north (I'm being facetious, but you get my drift ;) ). Hills, particularly at highway speed, really do sap this car's overall MPG in my experience.
     
  11. bamajoe

    bamajoe New Member

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    Thanks guys.. I'm not complaining just wasnt sure if it's doing what it should. Avg temps were around 50 I'd say and no rain but some wind out in the AZ. I average around 40 around home also but I attribute that to living right off a 65mph 4 lane and my driving style

    Posted via the PriusChat mobile app.
     
  12. fuzzy1

    fuzzy1 Senior Member

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    I must very strongly dispute this claim. Lack of regeneration at steady highway speed has absolutely nothing to do with the lower Highway MPG rating.

    Regenerating energy through lossy conversion processes is always is less efficient than transmitting it directly to the wheels in the first place. The purpose of regeneration is to recover energy that would otherwise be thrown away via friction braking. But at steady highway speed (on level roads, the only kind used for MPG testing), there is absolutely no energy being thrown away through this process.
    Higher speed creates greater air drag loss. In normal operation, that is the entire reason for Prius's greater fuel consumption at greater speeds.


    As I've pointed out in other threads, the Prius' higher City MPG rating is mostly an artifact of the EPA scale's artificial fudge factors, tuned more for traditional non-hybrids than for Prius-type vehicles. If you go back to the underlying CAFE highway and city ratings, before the EPA scale factors (and additional tests) are weighted in, that difference vanishes.
     
    #12 fuzzy1, Dec 1, 2018
    Last edited: Dec 1, 2018
  13. FuelMiser

    FuelMiser Senior Member

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    I will agree that lack of regeneration has very little to do with lower MPG than the speed itself, but I will not agree it has absolutely nothing to do with it. If you watch the Energy Monitor during steady highway driving, you will see energy diverted from the ICE to recharge the battery at regular intervals. At other times, the traction battery is contributing to forward motion. The reason, I believe, is that the Prius wants to keep the traction battery at some nominal state of charge at all times. The only way to do this is to spend some gas to recharge the battery. NOTE: I am not talking about EPA Ratings at all, just real world MPG observed at the wallet.