Steady State Speed vs Fuel Economy results

Discussion in 'General' started by seftonm, Mar 22, 2014.

  1. RedylC94

    RedylC94 Well-Known Member

    That looks like it can't, at any constant speed, touch the efficiency Gord is typically scoring .

    At what stage is energy measured for those numbers---leaving the battery, going into the motor, or where? There must be sizeable losses between the kw-hr meter used for billing (if one is charging at home) and the motor input.
     
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  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi RedylC94:

    Public Chargers measure the energy from the charger. There are losses going into the vehicle of course.

    The Taycan is a completely different animal when comparing to Gord's Model 3. I have never completed a Speed vs Energy Consumption with a Model 3 so I am not sure.

    Wayne
     
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  3. RedylC94

    RedylC94 Well-Known Member

    Certainly, but at what stage is power typically measured for short-term distance-energy ratios like those in your graph, or Gord's short trips? Battery output or motor input, or something else?

    Thanks!
     
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  4. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi RedylC94:

    Speed vs Fuel or energy is always measured vs the onboard storage. I cannot measure losses upstream

    The Taycan's results however show that its rated efficiency and range fall far short of actual.

    Wayne
     
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  5. seftonm

    seftonm Veteran Staff Member

    That's impressive! I've read in a few places that the Taycan's range is underrated, but it's nice to see it confirmed with your usual attention to detail.
     
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  6. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    The calibration drive consisted of 261.4 actual miles traveled vs 258.7 miles indicated from initial top off to final calibration top off.

    The Niro took almost 2-gallons more after first shutoff and maybe 15-minutes in total to top off.

    261.4 miles on 4.062 gallons = 64.35 mpg actual vs 67.4 mpg indicated resulting in a negative 4.2 percent negative aFCD offset. This is well within line of previous vehicles we have tested.

    2022 Kia Niro HEV

    [​IMG]
    Initial top off with displays reset.

    [​IMG]
    261.4 actual miles on 4.062 gallons top off to top off.​

    For the steady states, temps ranged from 46 to 50 degrees F with winds calm on the multiple NB and SB runs. From the calibration drive, the aFCD offset came in at 0.958 * aFCD. Only 4 of the 10 runs had a SOC difference from start to finish and I added or subtracted 1.5 mpg depending if it was a 1 bar added or 1 bar subtracted.

    [​IMG]
    Just minutes after completing the steady states early this morning. 02:10 AM PST to be exact. ;)

    [​IMG]

    Using straight line analysis, the EPA highway (46 mpgUS) crossover occurred at a somewhat low 64.7 mph. The larger 18s surely took the 2022 Kia Niro EX Premium to the woodshed vs the 16's on the std. Niro Hybrid trims for example. The EPA highway for the Niro EX Premium trim (67.5 mph) occurs at 42.85 mpg highway rating so 43 mpg highway is what it should actually be rated at with those larger wheels and tires.

    Wayne
     
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  7. BillLin

    BillLin PV solar, geothermal HVAC, hybrids and electrics

    I'm guessing the speed-economy curve should never have a positive slope, so the curve fitting algorithm may need tweaking given the 55/60 mph data points.

    re: wheel size - Wow. It is so cool that your testing is able to put numbers on the impact of less efficient wheels.
     
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  8. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Bill:

    I am sure if I would have taken a 4 sets of NB/SB runs between 50 and 55 mph, that slope would have been flat to slightly negative. The only time I remember seeing an actual positive slope was on a 2017 (???) Camry V6 w/ a 6-speed AT we tested way back with an increase of a mpg or two between 50 and 55 mph.

    Whenever I see a Monroney with the larger "premium" wheels arrive, I cringe. :(

    2022 Kia Niro EX Premium Hybrid Monroney

    [​IMG]

    Wayne
     
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  9. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    Another all-electric that performed extremely well on the CleanMPG Speed vs FE charts.

    2022 AWD Audi GT RS with an 84 kWh useable battery and 21" summer Goodyear F1 Performance tires (232-miles AER) EV Calibration Drive

    [​IMG]
    [​IMG]
    Topped off…

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Reset (0.0 miles/KWh) to 3.8 miles/kWh over 300.3 miles indicated, 303.3 miles actual.

    But first, the Audi's DCFC spec is 5 to 80% in 22 to 23-minutes but just like the Porsche Taycan, 5 to 80 percent occurred in a staggeringly fast 19-minutes! Whatever SW updates the VW Group has done to the Porsche has also been uploaded into the Audi and it kicks @$$. :D

    [​IMG]

    88 KWh from 5 to 100% SOC indicates it would take ~ 92 KWh to charge from 0 to 100%. If the maximum actual useable pack capacity is 84 KWh, this indicates a charging efficiency of just 91.3 percent. I thought it would have been higher. Or that more than 84 KWh is useable? A Question I have not found an answer too.

    In any case, 303.3 miles (actual) on 88.15 KWh = 3.44 mi/kWh. If the actual pack charge was 84 KWh * .95 (5 to 100%) or 79.8 KWh added to the pack and not lost to heat from the cable to the Inverter to the pack, this would indicate 303.3 miles/79.3 KWh = 3.82 Miles/KWh which is almost exactly what the Audi display indicates at 3.8 mi/KWh. I used a 0 percent offset for that Speed vs Energy Economy curve.

    [​IMG]

    The EPA highway rating of 2.43 miles/kWh was deduced from the Audi GT RS’ EVs 82 MPGe highway/33.7 kWh/gal.

    79/82 MPGe (city/highway)/33.7 kWh/gal = 2.34/2.43 MPGe (city/highway)

    Temps from 52 to 54 degrees F, Winds calm.

    The EPA highway crossover (2.43 mi/KWh) occurred at 73.375 mph. Compared to its EPA rating at 67.5 mph = 2.82 mi/KWh, this indicates the EPA range highway should be 271-miles, not 232-miles from the combined number.

    When comparing the above graph of the AWD 22 Audi GT RS with the 21" wheels and sticky summer performance Goodyear F1s vs the RWD Taycan with 19" Continental ProContact All-seasons, the efficiency fall off is poignant!

    Consider both vehicles efficiency at 70 mph.

    RWD Porsche Taycan w/ All-season 19s - 3.12 mi/KWh
    AWD Audi RS GT w/ Summer Performance 21s - 2.7 mi/KWh

    The efficiency fall off is 15.5%!

    While not nearly as efficient as the 2021 RWD Taycan w/ 19’s and all-seasons, the AWD GT RS is a bit more efficient than its 2.32 miles/kWh rating around town as well.

    Wayne
     
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  10. thunderstruck

    thunderstruck Super Moderator

    Couple of things of interest on my new one. The car will shut the ICE off when CC is on, unlike my 2016 Prius would do. TCH seems to want to settle at 1280 RPM which again rings a bell. It also will drop a lot on the back road here which is rated at 55 MPG down to 992 RPM but with ICE using 0 GPH. Engine defuels but does not shut off for some strange reason. Then all of a sudden it shuts off. I need more seat time and more eyes on SG before I can figure this thing out.
     
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  11. litesong

    litesong litesong

    Wayne posted:……..Goodyear F1 Performance tires

    litesong posted: I’ve got 2 free used Goodyear F1 tires (with quite a bit of rubber) to eventually use on our Hyundai Elantra. So we’ll see how they work. I’ve already had 4 free used tires that worked smoothly & quietly on our cars.
     
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  12. RedylC94

    RedylC94 Well-Known Member

    Coincidentally or not, those are exactly the same speeds my Prius engine favors when warming up, and when coasting with fuel cut off at more than about 45 mph, respectively. Minimum engine speed when it's producing any power (typically during slowish steady forward speed on a level stretch) is slightly slower, but harder to pin down.
     
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