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Thread: The effect of using cruise control to accelerate on fuel efficiency

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    The effect of using cruise control to accelerate on fuel efficiency

    I have recently bought a 2016 Mirage (CVT) with a cruise control and looking for the most efficient way to drive the car.
    I love driving with a cruise control, but I have noticed that when it is used to accelerate by holding the swith into + position, engine revs up to around 3000-4000 RPM until reaching the desired speed. At the same time, if the speed is increased gradualy by a single "press" of the + switch, engine runs at relatively low REVs.

    Would you think that is more efficient to accelerate with a cruise control pushing up REVs, or gently using an acceleration pedal?



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    Moderator Eggman's Avatar
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    That's a good question. I would expect gentle acceleration would be better for fuel economy. How can this be measured?

        __________________________________________

        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 ... 59.5 mpg (Imp)


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    Senior Member IchabodCrane's Avatar
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    You do not use cruise control to bring the car up to speed.
    The purpose of the +/- is to bump cruise speed up/down while in cruise to adjust speed according to traffic etc.
    Get the car up to cruising speed with the accelerator pedal, engage cruise and adjust as required.
    As for fuel economy.. There is no fuel saving potential in a high rpm race to cruising speed. None.
    Note that being aggressively gentle and taking too long to reach cruising speed is also detrimental to fuel economy.
    The most efficient form of accelleration is a balance of reasonable throttle vs time getting to cruise speed.
    I'm in my second cvt Mirage and I use cruise at every opportunity. I see very good economy numbers without much effort.
    The cvt trans is nice in that you can hold the accelerator at a specific rpm and allow the car to cover a very wide range of speed. Personally I try to keep rpm around 2100 or less in cruise and I +/- as needed to maintain this as an average, around 60 - 65 mph.
    For me acceleration to cruise is handled by holding 2500-ish rpm until 60mph then on cruise.
    If conditions require it, I run rpm up to 3000-ish to get there. Rarely will I accellerate at higher rpm unless passing or getting out of the way.
    With this method I get daily average commute economy (avg. of both directions) which right now includes detour on gravel country road, highway and rural 60 km/h road of 4.7 to 4.9 L/100km. Total daily commute is 55 miles on average.
    Last edited by IchabodCrane; 06-20-2018 at 03:42 PM.
    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 IchabodCrane View Post
    There is no fuel saving potential in a high rpm race to cruising speed. None.
    Note that being aggressively gentle and taking too long to reach cruising speed is also detrimental to fuel economy.
    The most efficient form of accelleration is a balance of reasonable throttle vs time getting to cruise speed.
    I would have guessed that in this case a better fuel economy could be associated with a lower brake specific fuel consumption at 3,000-4,000 RPM. Keeping the engine at low RPMs coud be reasonable if a low power output is required. However, these are just assumptions and I would like to discuss it further and hear your thoughts.

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    Senior Member IchabodCrane's Avatar
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    You dont have much choice here with the cvt. It aggressively hunts the lowest rpm while in cruise.
    But to test the hypothesis of better economy around 3000rpm you could run in DS mode and see if it's better or worse in comparison.


    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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