46.9 mpg highway? New to me 2015 two.

Discussion in 'Gen 3 Prius Fuel Economy' started by Jon Watkins, May 30, 2018.

  1. Jon Watkins

    Jon Watkins Member

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    Bought a 2015 two last night for my wifes daily. 37k miles, one owner, all maint on time at the dealer. 15k. First time owning a gen 3. We also have a 2017 three that is my daily.

    I drove the 2015 home last night after picking it up in Jacksonville. The drive on the interstate was about 175 miles and flat interstate all the way. Cruise was set at 70 and the winds were calm. AC was on the whole way. The tires are cheap Chinese junk and are going to be replaced this week. The alignment is also off and that will be fixed when the new tires are installed. Display showed 46.9 mpg when I got off the interstate near my home. That mpg doesn’t seem to be great for those conditions. The 2017 got slightly over 60 mpg.

    I reset the trip for the 10 miles from the interstate exit to my house and avg 55 mpg. That was a combination of 55mph and subdivision.

    What are your thoughts on that highway mileage?
     
  2. Raytheeagle

    Raytheeagle Senior Member

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    Sounds about right ;).

    What were the air pressure in the tires?

    On our 2010 with 180k miles if I travel at 70 mph that’s about what I would average. But I travel about 5 mph slower and get 49-50 mpg:).

    Good luck with your new Prius (y).
     
  3. Salamander_King

    Salamander_King Senior Member

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    I used to drive 2015 Two. I only had it for 3 years littell over 30K miles. Overall mileage was 52 mpg (calculated). I think your number is very similar to what I was getting on mine. Yeah, new good LLR tires will improve that number.
     
    #3 Salamander_King, May 30, 2018
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  4. Jon Watkins

    Jon Watkins Member

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    Pressures were 39 front 38 rear.
     
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  5. Raytheeagle

    Raytheeagle Senior Member

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    That’s close to what I run our Bridgestone Turanza Serenity tires on the Prius at;).

    There a great tire (quiet and last a long time). Currently at 60 k miles on them and have about 7/32” left:).

    I’d buy them again(y).
     
  6. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Don't read too much into that. Check the engine underpanel, dealerships tend to be hard on it. Also have the brakes checked, and just be ready: there may be over-torqued bolts, on the wheel lug nuts, the oil pan drain bolts, and the oil filter. Depends a lot on the mind-set of the dealership.

    Some owners that do all-dealership service, not all but you never know, tend to be COMPLETELY hands off. Never do oil level checks between oil changes, for example. And it seems there's a lot of reports, dealership service but completely neglected brakes. Still, at only 37K miles, not much can happen.

    That sounds about right. 70 mph is getting up there, and AC will impact mpg.

    Yup, but look at Fuelly stats: 4th gen is head-and-shoulders above 3rd. Bear in mind displayed (for both gens) tends to BS, about as much as Toyota can get away with, without it becoming totally embarrassing. Other factors, it's an older car, with questionable tires.

    That too sounds ok, for 3rd gen.
     
    #6 Mendel Leisk, May 30, 2018
    Last edited: May 30, 2018
  7. MelonPrius

    MelonPrius Active Member

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    I have the contrarian opinion. 46.9 mpg on display would be ~45 mpg hand calculated, which is too low for the conditions you mentioned. Assuming that the elevation was the same and you were driving solo, you should have been closer to 53-55 mpg on the display- but you didn't go round trip. When I drive around Vegas, I can have a difference of 20 mpg on return trips on the highway.

    When I purchased my Prius, I had a 5 hour drive to return home. I did what you did- set the cruise to 70, enjoyed the AC, and saw 55 mpg on the display after 300+ miles.

    I wouldn't fret too much until I see what a full tank brings, but I'd pay close attention. The easy fix is the alignment, which can create havoc on fuel economy.
     
  8. bisco

    bisco cookie crumbler

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    tough to compare two long drives like that. cheap tires might hurt. other things might need attending to, even at 37k.
    2017 is a far better vehicle in many ways.
     
  9. fuzzy1

    fuzzy1 Senior Member

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    But a Gen3 shouldn't quite get 55 MPG at 70 MPH without a tailwind, even with AC off:
    Updated MPG vs MPH chart | PriusChat
     
  10. Tideland Prius

    Tideland Prius Moderator of the North
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    I've never gotten 55mpg at 70mph with cruise control on my Gen 3.

    47mpg sounds about right (which is weird, considering your tires and alignment. When you fix those, you may gain a mpg).

    I recall the Gen 2 gets 5.1L/100km (46mpg) and the Gen 3 gets 5.0L/100km (47mpg) for me at 70mph with cruise control. You can certainly get much higher without cruise control (drop the speed to 50-60mph and no cruise - I got 62mpg with light traffic)
     
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  11. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Those are probably displayed mpg values? I'm not sure how it could be otherwise. Then it's apples/apples.

    The displayed will be optimistic, anywhere between 5 and 10 percent, fwiw.

    Very good graph for illustrating the impact of speed on mpg, btw.
     
  12. MelonPrius

    MelonPrius Active Member

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    Unless I'm reading the chart wrong, it seems to be accurate. 55 mpg "on the display" will be around 52-53 mpg hand calculated. That seems to be what the chart indicates.
     
  13. Jon Watkins

    Jon Watkins Member

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    Checked the tire pressures this morning before I drove to work. Cold pressures were 29 - 30 on all wheels. Idiot dealership!!

    We’ll see what the mpg’s are with 39 front and 37 rear.

    Getting it aligned tomorrow.
     
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  14. fuzzy1

    fuzzy1 Senior Member

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    But even the 'displa'y line doesn't quite reach 55 mpg at 70 mph. One needs to slow down to 65 mph or less to get that mpg.

    Add in tire and alignment issues, and one would need to slow even more to get a displayed 55 mpg.
     
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  15. jerrymildred

    jerrymildred Senior Member

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    Mine gets almost exactly 50 mpg indicated at 70 mph on level ground with no wind. That's with my wife along and using cruise control and A/C. So getting the alignment and tires taken care of, you should be right about there. For mine, running in HV mode, 60 mph is the crossover point. At 50 mph, I get 70 mpg. At 70 mph, I get 50 mpg. And at 60 mph, I get 60 mpg.
     
  16. MelonPrius

    MelonPrius Active Member

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    I have the same problem when I used to ask Costco to put air in my tires. No matter what I requested (they'd always say yes with a smile), they would walk to my front door jam and use that psi. Hopefully the higher psi and alignment will help the fuel economy.

    I've been looking to take a nice trip driving 60 mph. But those highways are difficult for me to find. Even with my local highways with a 65 mph limit, I often drive 70 mph (which is actually ~68 mph) so I don't hold up traffic.
     
  17. jerrymildred

    jerrymildred Senior Member

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    They are rare here, too. Most of them that have a 60 mph limit make you stop about every mile.
     
  18. fuzzy1

    fuzzy1 Senior Member

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    Hence, the Gen3's crude rule of thumb of 120: MPG + MPH is capped at about 120. Gen2 is capped lower, while Gen4 goes higher.

    The OP was seeing (46.9 + 70) = 116.9. That is plenty close when having the impairments of cheap tires and some alignment problem and some underinflation.
     
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