84 mpg with cruise control

Discussion in 'Gen 3 Prius Fuel Economy' started by zebekias, Aug 12, 2014.

  1. zebekias

    zebekias Member

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    Hello,

    I'm an American also living part of the year in Greece, so I bought a loaded lightly used (16k miles) 2010 Toyota Auris Hybrid from a Toyota dealership in Germany and drove it to Greece :) You name it, it has it: 17" rims, rain sensing wipers, NAV, keyless entry, cruise control, etc, DRL, and more. It has the exact same 3rd gen HSD as on the 2010+ Prius, so I'm posting on this forum because there is not much of a following for the Auris as there is for the Prius.

    The very first time I set out to do highway driving in Greece at 80 kph (50 mph) I got the incredible avg of 2.8 l/100 km (84 mpg) for a trip of about 60 km!!!!!!! Eco mode, A/C on. Not sure if I had a tail wind or if my start/end elevation difference is significant.

    The only technique I employed was to lower the CC when climbing significant hills to 70 kph, other than that the CC did all the work set at exactly 80 kph. In all fairness, I have not had the chance to do the same route backwards. The temperature the day I did it was a toasty 35 C (95 F.) Also, I have not been able to match this consumption driving around busier smaller curvy/hilly roads near my beach house. If I'm really careful I can get anywhere from 3.5 l to 3.9 l / 100 km (60 - 67 mpg) with the lower range to include some pulse and glide when possible. If I just use CC set to 80 kph I get the upper range if there are no huge hills. I have gotten as high as 4.1 - 4.3 l/100 km (55-57 mpg) for routes that go over mountains/switchbacks.

    I'm really impressed! I'll report back as I get more milage on the car.
     
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  2. bisco

    bisco cookie crumbler

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    welcome to priuschat! sounds really interesting, post some pics with scenery if you can, all the best!(y)
     
  3. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Very, very good numbers. We also have the 17" rims, and even without AC on are nowhere close to that. I agree the cruise can yield good numbers.

    Slight niggle: are your numbers calculated or what the car's saying. Either way good numbers!
     
  4. zebekias

    zebekias Member

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    The numbers I list are what the car says (avg consumption) so take them with a grain of salt :) From what I've read the prius is 4% optimistic, I don't know how optimistic the Auris is. Next time I do highway driving I'll top it off and fill it up immediately afterwards so I can gage how accurate the consumption reporting is.
     
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  5. tv4fish

    tv4fish Member

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    Those ARE very good numbers - however, I still maintain that one can get better mileage with an "educated" foot on the gas pedal and using "pulse and glide" (where applicable) than using the CC. I say this especially if you have hills of any size to contend with. IF we are talking "flat" roads, then I might lean towards the CC.
     
  6. zebekias

    zebekias Member

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    Yeah, for the nickel and dime hills it's clearly easy to do better than CC. For the major hills (that are no longer than 1-2 miles) is there a way to "tell" the computer to use electric assist (battery only, no charging) ? I've seen it happening automatically, especially with a high SOC.
     
  7. bwilson4web

    bwilson4web i3 and Prime

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    Welcome to the club!

    I did a driving stunt last summer that made extensive use of cruise control:
    Efficient driving for a 1,000 mile tank | PriusChat
    • 2.56 L/100km
    • 35 km/h
    • 1601 km
    • 41.26 L
    • ~3 weeks
    My only caution is charging NiMH batteries heats them. So I recommend using "B" when descending tall hills, 100 m, at high speeds to reduce the rate of heating. Also, take care to keep the cooling vents on the side of the rear seat clear and try to keep the traction battery as cool as practical. For example, park in a shady spot and walk a little further than close and solar heat the interior.

    GOOD LUCK!
    Bob Wilson
     
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  8. zebekias

    zebekias Member

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    I just got around to checking the elevation profile (google earth) of the 84mpg route

    start: 415ft
    finish: 77ft

    I got excited over nothing :-(
     
  9. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    ^ Getting excited about good mpg is half the battle. ;)
     
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  10. SageBrush

    SageBrush Senior Member

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    The decline saved about 1.17 kWh of fuel (m*h*g/0.36 in joules)

    Your 60 km run consumed 2.8*0.60 = 1.68 liters
    A liter of fuel contain about 8.8 kWh of energy (33.4 kWh/US gallon / 3.8 Litres/gallon )
    So the trip used 1.68*8.8 = 14.784 kwh

    On flat land consumption would have been 14.784 + 1.17 = 15.954 kWh
    (15.96/14.78)*2.8 = 3.02 litres/100 km on flat land

    You had some help from wind. 3.4 L/100km is about expected
     
    #10 SageBrush, Aug 13, 2014
    Last edited: Aug 13, 2014
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  11. bwilson4web

    bwilson4web i3 and Prime

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    Oh, did we mention Prius people also speak 'metric.' <GRINS>

    Bob Wilson
     
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  12. zebekias

    zebekias Member

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    On a side-note, I played around with google earth (on my macbook air) and it seems to be grossly inaccurate. If I hover over certain high points on the elevation profile, after a few seconds it zooms in on the point of the map that has that peak, and then the elevation profile is recalculated, usually resulting in a very different looking profile. How about a 2000 ft peak going down to a 500ft peak! I have to find another source of elevation profiles, I can't trust google earth.
     
  13. SageBrush

    SageBrush Senior Member

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    Amen.

    I can tolerate American for simple units like speed or weight, but I have to use metric for calculations or I make mistakes and find the units way too frustrating.
     
  14. zebekias

    zebekias Member

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    The jury is still out, especially since I'm not sure how trustworthy google earth elevation profiles are (see my previous post.)
    3.4 l/100 km is still 69 mpg which I'd be super happy with. My 2014 Nissan GTR in the states gets, brace yourselves... 18.5 mpg if I'm a good boy or south of 15 mpg when naughty. I've even heard reports of low single digits at the track lol. One thing is for sure, Toyota lists the Auris HSD with the 17" wheels at 4.0 L / 100 km, and that I am fairly confident on flat road, A/C on, and CC set to 80 kph is an accurate ballpark.

    In a week I'll be going from Thessaloniki to Athens (en route to Mykonos :) so I'll have a nice 500+ km highway baseline.

     
  15. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Metric can be maddening too, when all your components are imperial measure. Engineering projects for example (my personal nemesis). Or jus just trying to price compare supermarket products with translated to metric measure.
     
  16. SageBrush

    SageBrush Senior Member

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    Leave it to the Brits to make even metric difficult ;)
    They should have learned their lesson after losing leadership in Maths & Sciences due to Newton's stubborn refusal to accept Leibniz' superior notation, but Noooooo
     
  17. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Getting further and further off topic, but:

    I wish nothing but bad things to whomever it was that initially decided that there would be (approximately) 25.4 millimeters in an inch. It only added insult to injury when they revised it to be exactly 25.4...

    Up here they sometimes give missing persons reports in metric. Those people mostly stay missing I think. And I recall a news report some years back (wildly paraphrasing, but something like this):

    "A man drove into the 1245000 centimeter diameter by 1435000 centimeter deep water-filled sinkhole. By the time he was pulled out his core temperature had dropped to 28.5 centigrade."

    I had no clue if this was a significant event, lol.
     
    #17 Mendel Leisk, Aug 13, 2014
    Last edited: Aug 13, 2014
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  18. SageBrush

    SageBrush Senior Member

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    :)

    Don't worry about off-topic. We have at least ~ 8 hours until OP reaches Athens
     
  19. DoubleDAZ

    DoubleDAZ Senior Member

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    So you're suggesting that when I go down a hill for 100m/110 yds or more at 105 kph/65 mph, I should use "B" mode to minimize heating the batteries too much via regen during our trip to Yellowstone and Glacier. I have 2 such sections between Phoenix and Flagstaff and I'm sure there will be more in Colorado. Does this apply when gong slower? Here I'm thinking of going slower through the curves on the Beartooth Highway from Red Lodge to Cooke City MT.
     
  20. SageBrush

    SageBrush Senior Member

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    I'm pretty sure he means
    • 100+ meters of drop
    • riding the brakes down
    • the speed variable can be read as "max regen."
    You can parse the advice as "try to avoid going from 2 bars to 8 bars on the battery meter in under a minute" ;)
     
    #20 SageBrush, Aug 13, 2014
    Last edited: Aug 13, 2014
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