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Thread: Is the CVT really more efficient than the manual transmission?

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    Senior Member IchabodCrane's Avatar
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    Quote Originally Posted by Cobrajet View Post
    I am sure the CVT is fine for most people, but I just don't think it is worth an extra thousand damned dollars!
    No it's not. I prefer it though as I'm fully sick and tired of shifting gears.. I have been operating commercial trucks off and on for over 30 years. 140,000lbs every day in hills, towns and cities with 18 gears to shift.
    Every time I drive this car it feels like a midwinter vacation.


    Will weld for beer.

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        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 45.3 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.5 mpg (Imp)


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    Quote Originally Posted by Daox View Post
    My bet goes to the 5 speed manual in both conditions. Here is why:

    Speed vs. mpg/mileage/fuel economy chart - Mirage 1.2L 5-spd and CVT

    and

    Gas mileage/MPG test: 2014 Mirage CVT vs. 5-speed (sub/urban Ottawa route)

    That being said, the difference isn't gigantic. If you like the convenience of the CVT, you're going to take a hit, but its not the end of the world.
    What's confusing me here is that, in theory, the CVT can do any gear ratio the manual can, and more. How is it then that the manual is getting better MPG at 120km/h?

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    Senior Member 25Plus's Avatar
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    To answer the question, which gearbox is more fuel efficient, you only have to look at the fuel economy log:

    CVT automatic only 70 cars 41.1 MPG (US) = 17.5 KM/L = 5.7 L/100 km = 49.3 MPG (UK)
    5-speed manual only 70 cars 44.7 MPG (US) = 19.0 KM/L = 5.3 L/100 KM = 53.7 MPG (UK)

    Itīs the same here in Europe with the longer gear ratio of the 5-speed manual:

    5-speed manual only: 5.1 l/100 km
    CVT automatic only: 5.5 l/100 km / 5.4 l/100 km (many people donīt know the difference of the transmission types)
    Mitsubishi Space Star 1.2:
    Daihatsu Cuore L251:

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        click to view fuel log View my fuel log 2015 Space Star Klassik Kollektion+ 1.2 manual: 67.9 mpg (US) ... 28.9 km/L ... 3.5 L/100 km ... 81.6 mpg (Imp)


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    Quote Originally Posted by ecoboxer View Post
    What's confusing me here is that, in theory, the CVT can do any gear ratio the manual can, and more. How is it then that the manual is getting better MPG at 120km/h?
    That's a good question.
    1. The CVT still has a torque converter (aka slushbox)?
    2. The operator of a manual transmission controls the shift points, either for better or worse fuel economy.
    3. The data do not take into account speed.

    Just tossing out some ideas. I think MetroMPG, Daox, and others more versed in hypermiling can give better answers.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.6 mpg (Imp)


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    Senior Member IchabodCrane's Avatar
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    Quote Originally Posted by ecoboxer View Post
    What's confusing me here is that, in theory, the CVT can do any gear ratio the manual can, and more. How is it then that the manual is getting better MPG at 120km/h?
    the answer to this question is in the car specs. The graph is showing a Philippines spec. gearbox vs a US spec CVT.
    The difference being the Phillippine spec manual has higher gearing than the US spec allowing it to run lower RPM at high speed than a US spec manual.
    I don't know if all CVT's are the same or are ratios different in different markets?
    Will weld for beer.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 45.3 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.5 mpg (Imp)


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    Senior Member IchabodCrane's Avatar
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    Quote Originally Posted by Eggman View Post
    That's a good question.
    1. The CVT still has a torque converter (aka slushbox)?
    the torque coverter plays virtually no role in mileage numbers as it only comes into play starting from a dead stop and locks up almost immediately upon moving. This small slippage cycle would roughly equal the slippage/engagement cycle of starting from stop of the manual transmission.
    After this the torque converter stays locked throughout all gear ratios on the spectrum except possibly during the reduced power moment of shift from low to high aux gearbox.
    The manual gearbox has to absorb 4 shift points through it's range so theoretically should waste more energy between 1st and 5th gears going up and coming down.
    It seems theoretical and real world are not that tightly linked when it comes to driving..
    Will weld for beer.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 45.3 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.5 mpg (Imp)


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    Quote Originally Posted by Eggman View Post
    That's a good question.
    1. The CVT still has a torque converter (aka slushbox)?
    2. The operator of a manual transmission controls the shift points, either for better or worse fuel economy.
    I don't think these would come into play when driving a constant speed on the highway. Torque converters do lock up at high speeds, they really only unlock to prevent the engine from stalling when stopped.

    Quote Originally Posted by IchabodCrane View Post
    the answer to this question is in the car specs. The graph is showing a Philippines spec. gearbox vs a US spec CVT.
    The difference being the Phillippine spec manual has higher gearing than the US spec allowing it to run lower RPM at high speed than a US spec manual.
    I don't know if all CVT's are the same or are ratios different in different markets?
    Interesting, I see now that there are two seperate manual gearboxes for different regions of the world.

    Can anyone with the US 5 speed manual confirm what MPG they are able to achieve at highway speeds in 5th gear?

    It still doesn't make sense to me that the 5 speed would get better mileage when it revs at such a higher RPM on the highway. I always assumed that lower RPM = lower fuel consumption because of reduced friction.

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    Senior Member MightyMirageMpg's Avatar
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    Quote Originally Posted by ecoboxer View Post

    Can anyone with the US 5 speed manual confirm what MPG they are able to achieve at highway speeds in 5th gear?

    It still doesn't make sense to me that the 5 speed would get better mileage when it revs at such a higher RPM on the highway. I always assumed that lower RPM = lower fuel consumption because of reduced friction.
    MPG's fluctuate so heavily based on conditions and driver its almost insignificant to put a number out.

    The automatic achieves lower RPMs but also consumes lots of power itself to operate. Making it drastically less efficient than any manual offered in a mirage. The effects would be shown in city driving, with The auto loosing to the stick.

    But because the auto transmission allows such a low final drive (.54 ideal as stated by INUVIK) it allows the engine to spin drastically slower speed then the manual and therefore the engine itself consumes less fuel, (but it's still being robbed of the cvt draw)

    At some point, the amount of fuel lost by excess RPM exceeds the fuel lost by the draw of the CVT. For your "average" driver that doesn't employ tricks or techniques to save fuel, the speed is probably about 65mph, where the cvt begins to get better MPG

    There's a little more to be discussed but simply put I've not seen any data that referenced engine load at speed manual vs automatic, and unless you have a lot of patience and the fuel map for the car... The data is useless anyways.

    Hopefully i explained that well enough its hard to explain in text
    Last edited by MightyMirageMpg; 01-22-2017 at 09:41 PM.

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    Quote Originally Posted by MightyMirageMpg View Post
    MPG's fluctuate so heavily based on conditions and driver its almost insignificant to put a number out.

    The automatic achieves lower RPMs but also consumes lots of power itself to operate. Making it drastically less efficient than any manual offered in a mirage. The effects would be shown in city driving, with The auto loosing to the stick.

    But because the auto transmission allows such a low final drive (.54 ideal as stated by INUVIK) it allows the engine to spin drastically slower speed then the manual and therefore the engine itself consumes less fuel, (but it's still being robbed of the cvt draw)

    At some point, the amount of fuel lost by excess RPM exceeds the fuel lost by the draw of the CVT. For your "average" driver that doesn't employ tricks or techniques to save fuel, the speed is probably about 65mph, where the cvt begins to get better MPG

    There's a little more to be discussed but simply put I've not seen any data that referenced engine load at speed manual vs automatic, and unless you have a lot of patience and the fuel map for the car... The data is useless anyways.

    Hopefully i explained that well enough its hard to explain in text
    No this was a great explanation. Is the CVT electric or hydraulically powered?

    Also, does anyone know the stock DFCO settings for the Mirage? On my Chevrolet it enables after 4 seconds on the auto transmission and 2 seconds on the manual, if the engine is above 1100RPM and 50°C.

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    Senior Member IchabodCrane's Avatar
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    Isn't there a thread showing rpm at certain speeds re manual vs cvt here on the forum?


    Will weld for beer.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 45.3 mpg (US) ... 19.3 km/L ... 5.2 L/100 km ... 54.5 mpg (Imp)


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