Potiential Prime Buyer, need advice on mpg

Discussion in 'Prime Main Forum (2017-Current)' started by Redoubt, Aug 8, 2019.

  1. Redoubt

    Redoubt New Member

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    Hello I am considering purchasing a Prius. The other day I test drove a regular Prius le and managed to get 85mpg in city traffic. I am looking at either an AWD or the prime premium.

    I test drove a prime today with a flat battery as it was not charged and only had 5 miles on the odometer. I wanted to test the mpg when the battery is depleted to see what I would relastically get and if it would be the same as the Prius le model I drove.

    Well I could not get above 50mpg doing the same driving. Why is this?
     
  2. schja01

    schja01 One of very few in Chicagoland

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    I get low to mid 60s in summer without thinking about it in HV mode FWIW.
    Though I don’t spend a lot of time in HV mode.
     
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  3. Rob43

    Rob43 Senior Member

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    Welcome to PriusChat !

    ************************************

    Quick question, what do you pay for a gallon of gas currently and how much does 1 kilowatt of electricity cost you with all taxes and fees ?

    EDIT: Based on your EXTREME residential electrical cost, don't buy a Prime.


    Rob43
     
    #3 Rob43, Aug 9, 2019
    Last edited: Aug 9, 2019
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  4. wb9tyj

    wb9tyj 2017 Prius Prime Advanced

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    you are probably better off in a regular prius , given that the prime EV range is only in the neighborhood of 25-35 miles on a full charge ...and like rob43 said .your electric rates are way too high to charge economically...but your gas is too...to answer your question of why the prime was doing less mpg than a regular hatchback was ,in part, the prime weight is a bit more than the hatchback weight...( 3010lbs vs 3375lbs) +/- ...and i would bet the tires may need air and if the battery was depleted, i would venture to say the dealership has no clue how to optimize the prime and charge the battery and let the EV/HV work together to maximize mileage...
     
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  5. jb in NE

    jb in NE Senior Member

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    I would put very little faith in the indicated mpg in the dash from a short test drive. One engine could have been warm, the other cold. Tires different pressures, different drive modes, etc. The Prime is EPA rated for very similar mileage as the regular Prius when running on gas.

    A few things to consider - if you have home solar, you can charge the Prime with that. If any nearby locations offer free charging, that is free. With available tax credits, the Prime may be cheaper to buy.

    Do the math for your electricity and fuel costs and with same mpg estimates for gas see which mode is cheaper in the Prime. If gas wins, then get the Prius.
     
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  6. Trollbait

    Trollbait It's a D&D thing

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    Lots of variables could be at play. My bet is that the Prius had a warmed up engine, and the Prime did not. My Camry will display mid thirties for a trip. If I reset the monitor after the engine has warmed up, the display will then go into the forties.

    The best way to gauge what a new car will return in MPGs for you is to know what you get in your current car. What you are getting in relation to that model's current EPA rating will generally be about the same to any other model. If you are beating it, you'll beat it in a new car. Getting worse, how much worse will be about the same as a percentage.

    The Prius and Prime are the same car; only difference is battery size. That big battery actually helps the Prime get a better MPG rating than the Prius, only Eco Prius is rated higher. So on the same drive with all the same conditions(engine temp, tire pressure, etc), the actuall fuel used will be about the same between them.

    In actual use, the Prime may display a worse fuel economy. With part of a trip driven on energy from the grid, the miles on the engine will effectively be a short trip, and the hybrid efficiency will suffer the same penalty as a Prius driven on trips too short to fully warm everything up. But while the MPG during hybrid miles might be low, the miles driven on electricity means your total gasoline use will be lower than with a Prius. You may never have the ICE come on during your daily drive.
    Compare Side-by-Side


    Personalize the Fueleconomy.gov page with $3 gas, and the Prime costs less to fuel on gas. Electricity will cost more, but money is just one cost. Depending on the island, the renewable mix can be high, and many homes have solar panels in the state. Over 11% of their production now comes from solar.
    Hawaii Solar | SEIA

    It's Hawaii. Average annual miles there is under 10 thousand. Daily commutes a likely also shorter in comparison.

    The Prime is heavier, but the larger battery allows much more energy to be recaptured from braking. That's why it has a better EPA rating than the non-Eco Prius. Aerodynamics and ICE drive train are the same.
     
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  7. Rob43

    Rob43 Senior Member

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    Yep, I was NOT calculating any Federal Tax Credit when examining the gas vs electric costs.

    OP, please weigh all cost factors so you can make your best purchase, this also would include any future re-sale down the road.


    Rob43
     
  8. bisco

    bisco cookie crumbler

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    the reason is that the computer doesn't calculate real mpg when there's a charge in the battery.

    welcome!
    it calculates total distance divided by gallons used. well, some of that distance was provided by electricity.

    it could calculate distance with the engine on, and actually does on the percent ev/hv meter. but it does not use that to calculate mpg's.

    toyota wants you to believe the hype. in fact, the hv mpg's are optimistic as well. wait until you fill up and do a manual calculation :eek:
     
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  9. smyles

    smyles Active Member

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    Long term, Prime and regular Prius will yield comparable mileage in hybrid mode; but even with high kWh cost, I'd still recommend Prime as it drives so much nicer in EV mode that it even worth a premium.
     
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  10. jb in NE

    jb in NE Senior Member

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    Aero is slightly worse on the Prime due to the funky front end.
     
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  11. Usle

    Usle Member

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    After 22,000 miles my overall mpg with a prime is 92.3 mpg, in my 16 model 4 prius it was in the 50's like my 11' and my 06, the body for the prime is the same as the helium fueled model available now, it's different than the prius. Can't find aerodynamic efficiency figures, que sera sera
     
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  12. jb in NE

    jb in NE Senior Member

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    This does not include the electricity from your wall socket, only the gasoline use. This number shows only a part of the energy used to propel your car.

    Hydrogen?
     
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  13. killzone4

    killzone4 New Member

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    Wow is electric really $0.31 per kw in Hawaii! Outch. Based on my fast math
    (0.31×6.6)÷25×54=$4.42 per gallon is your break even on gas vs charging. So, prime may not make sense there.

    Also, Hawaii isn't known for snow and ice, so why is the awd Prius on the shopping list?
     
  14. FuelMiser

    FuelMiser Senior Member

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    Why do you want AWD in Hawaii? There's no way a Prius LE will get 85 MPG in all-around driving. Don't get a Prime unless you can plug-in at work...
     
  15. Trollbait

    Trollbait It's a D&D thing

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    Toyota reps stated at the time of the release that the back end improves aero, so the net is the same as the Prius.

    If they were lying, then the Prime gets better fuel economy in hybrid mode than the non-Eco Prius despite being heavier and having worse aero.

    You can plug in kWh rates in addition to fuel prices at Fueleconomy.gov. At that rate, it reports the Prime on electric costs 55 cents more to go 25 miles on electric than on $3 gas. I saw reports of even higher electric rates, but also some that state one in 5 homes on one of the islands has PV. There is more to consider than just the money cost.

    Unpaved roads can be a concern. I don't think the Toyota gives the AWD model a tow rating in the US.

    To clarify for the OP, because the sales critter likely didn't, the AWD system on the Prius is a low speed, low power one.
    "It will apply power as needed up to 6 mph when accelerating and up to 43 mph when the computer senses that additional torque is needed (when the front wheels slip basically)." - Toyota Finally Offers The Prius With AWD In The U.S. | Top Speed
    If AWD is being considered for performance, don't expect it from the Prius system.
     
  16. jerrymildred

    jerrymildred Senior Member

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    I can't find it again, but I read that the wave treatment in the rear didn't completely pay for the loss at the front. The article said that the lift-back cd is 0.24 and the Prime is 0.25. But just now, I saw an article claiming that the Prime is 0.24. Either way, both cars are pretty slippery.
     
    #16 jerrymildred, Aug 10, 2019
    Last edited: Aug 10, 2019
  17. drash

    drash Senior Member

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    Well you are hauling around an extra 200+ lbs around and the hills and off-ramps will penalize a little more. Knowing traffic and the roads in Oahu, the Prime's 8.8KWh battery will soak up the hills going down H2 particularly when you hit those 45mph areas. You will get penalized for going back up H2 to the mountains unless you have EV range left and are using EV Auto in which the ICE can assist. Or you can use CHARGE mode going down H2 to get a little extra EV, but I'd rely on regen. Those are some great hills for regen and you can shift into B (if you have EV range) for even more regeneration.

    So with the AWD Prius, you planning on going off-road or beach parking? I found it amazing how many people have AWD SUVs there.
     
  18. PT Guy

    PT Guy Active Member

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    Was it downhill both ways? I don't trust that number. As noted above a couple of things could have contributed to the inaccurate reading.

    We don't have enough gasoline-only city travel to give a report. Almost of our in-town driving is electric. The total mpg for our Prime driving is about 120...that's electric + gas miles ÷ gallons of gasoline. While the large Prime battery adds weight, it also makes it a better hybrid due to that larger battery. Aero won't matter much at city driving speeds. Aerodynamic resistance varies (almost) as the square of the speed.
     
  19. jb in NE

    jb in NE Senior Member

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    As the cube of speed, not the square.
     
  20. D.A.L

    D.A.L New Member

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    hows this...2020 prime...and i missed one full charge. Highway and city combined.
    20190731_091735.jpg
    that was a couple of weeks ago. now im at 2180kms at an average of 3.4 ltrs/100kms...70mpg...and missed two full charges. Tough to beat that. No?

    P.S. I get 50 to 60 kms on a full charge depending on torain. Mostly at 85 kpm.
     
    #20 D.A.L, Aug 10, 2019
    Last edited: Aug 10, 2019
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