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Thread: Tested: Speed vs. MPG/fuel economy, 2015 Micra SR automatic & Micra S 5-spd manual

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    Administrator MetroMPG's Avatar
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    Tested: Speed vs. MPG/fuel economy, 2015 Micra SR automatic & Micra S 5-spd manual

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    For your viewing pleasure and eco-driving enlightenment, may I present a graph showing cruising speed vs. fuel consumption in the Micra SR automatic that Nissan loaned me a little while back.

    - - - - - -
    UPDATE: also see post #8, below, for the results for the Micra S 5-speed loaner.
    - - - - - -

    (Yes, I'm still going through my notes, posting up interesting info.)

    Route: This info was gathered on a straight & level, 1.6 km / 1 mile stretch of dry road using a ScanGauge that was calibrated against 2 actual fill-ups. The numbers are averages of 2-way runs for each speed (except for the highest one), to average out effect of wind & grade. There were never any vehicles ahead of me in my lane (no drafting effect).

    Weather conditions (Mon, Jul 14, 2014):
    - Temp: 16C
    - Wind: WSW 2 kts
    - Press: 101.1
    - Humidity: 93%

    A/C was off, and cruise control was used for the test: set once for each speed, cancelled with the brake at the end of the first run and "resumed" for the run in the opposite direction to ensure the same speed each way.

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    Other notes...

    - I went by the Micra's indicated speed (which we know reads a little high). So shift the plot to the left by the right amount if you want to fine tune it even more.

    - That blip in the numbers between 50 & 60 km/h is there because the Micra's automatic transmission shifts into top gear and locks the torque converter right around 58 km/h under light load, making that the car's most efficient cruising speed (lowest engine RPM in top gear).

    Does this mean you should expect to get 5.7 L/100 km if you head out on a highway trip and set the cruise at 100 km/h?

    Not necessarily. Ever heard the saying "your mileage may vary?"


    • These numbers don't take into consideration the extra fuel burned getting up to speed.
    • The route was very flat; in hills, you'll likely get worse mileage.
    • There was almost no wind (and the 2-way runs average out its effect). In a headwind/crosswind you'll get lower fuel economy; in a tail wind you'll get better.
    • 1 person on board: no passengers & no cargo.
    • Weather was very MPG-friendly: mild temps. Winter conditions will have a big negative effect on these numbers.
    • No A/C use -- A/C drops the Micra's fuel economy.
    • The road was dry and smooth (pavement in good condition).
    • etc. etc.


    All of these variables will affect the numbers.

    I do this test with every car I own to have a benchmark of what I can expect on a round trip under good conditions. (Also I want it for comparison purposes, since I tend to modify my cars to improve mileage.)

    The moral of the story: speed kills MPG.


        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...


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    Daox (09-12-2014)

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    Great testing Darin!

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    Administrator MetroMPG's Avatar
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    Thanks.

    I was hoping to be able to compare speed numbers to a 5-speed Micra in the same conditions. The nice people at Cornwall Nissan even offered to let me take one for a spin... but they didn't have any in stock (like everybody else, it seems) while I had the SR automatic on loan from Nissan.

    But they did get one this week. So I may yet go do a city/hwy loop comparison between the two transmissions -- a head to head run.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...


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    Senior Member AlphaMicra's Avatar
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    Is it linear all the way to 100mph, or is there a point at which the laws of diminishing returns kicks in?

    In our culture obsessed with absurd excess, the Nissan Micra is my counterculture car of choice.
    Be sure to visit my blog at mymicra.com!

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SV manual: 6.4 L/100 km ... 44.3 mpg (Imp) ... 15.7 km/L ... 36.9 mpg (US) ...


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    thank you

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    Whats awesome is that if I drive 120kph in the micra I am still getting well over double the milage as my JK unlimited Jeep. ha ha!..

    My jeep at 120 gets on average 14-17per 100 km.

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    Administrator MetroMPG's Avatar
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    Quote Originally Posted by AlphaMicra View Post
    Is it linear all the way to 100mph, or is there a point at which the laws of diminishing returns kicks in?
    It wouldn't be a straight line if you tested to really high speeds, but the plot never "levels out" -- it takes on a bit of a curve for many cars.

    Auto Bild Magazine in Germany tested a bunch of cars to over 100 mph (some up to 155 mph):

    Attached Images Attached Images  

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...


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    Administrator MetroMPG's Avatar
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    Micra S 5-speed results

    Here are the results for the Micra S 5-speed that I borrowed from Nissan last month. Weather conditions were coincidentally very similar to the SR test day.

    Name:  $$speed-vs-mpg-2015-Micra-S.jpg
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    Notes:

    1) Numbers are ScanGauge readings, corrected 6% after calibrating against 2 fill-ups.

    2) I think the swerve in the results at the 90 km/h mark is probably some testing error.

    3) Notice how the automatic Micra seems to get a little bit better mileage than the 5-speed at 60 km/h and above?

    That's because when its torque converter is locked, the auto Micra actually has taller gearing than the manual. (Engine revs lower at a given road speed.) So on a long enough strictly highway run that kept the t.c. locked in top gear the whole time, the auto could use less gas than the manual.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...


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    Daox (07-24-2015)

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    Woohoo, that is some good testing. Also goes to show how taller gearing does improve fuel economy.

    Where is the graph with both lines on it?



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