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Thread: Awful MPG and performance with AC on (Mirage / Space-Star 2015)

  1. #1
    Junior Member smiba's Avatar
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    Awful MPG and performance with AC on (Mirage / Space-Star 2015)

    Hey everyone,

    I'm the owner of a 2015 Space-Star Bright 1.0 with manual transmission

    Recently the weather has been getting warmer and I've sadly found the need to use my A/C , otherwise I feel like I'm just torturing myself for some higher MPG .
    However I've found that although the A/C works perfectly and gets the cabin cool in less then a minute, the car loses nearly all of its power most of the time.

    It feels like the A/C is using a good part of my fuel, for example I usually drive 52 to 64MPG (US) when its not summer, however on just hot or moderately warm days like today with the A/C on I get a piss poor MPG of between 29 to 44MPG (US).

    It get so bad that sometimes I'm actually having issues properly driving away with this car without the need to ramp the RPM up to as much as 3000RPM while slowly releasing the clutch. Trying to drive away with sub-2000RPM numbers will directly cause the RPM's to drop and almost choke the engine. (Although it never actually ended up choking the engine, partially because I'm quick to press the clutch again to prevent this from happening).

    Also while driving it causes unease, because the throttle will become much more sensitive and the rolling distance of the car is absolutely awful and more feels like you're breaking. Especially when driving in traffic in first or second gear its pretty bad, to the point where its much more comfortable to just give some gas and then roll further with the clutch pressed in. (To disconnect the engine from the wheels)

    Is this normal? Am I a fool for thinking the A/C shouldn't almost use 50% of my fuel?
    This behaviour directly stops when I disable the A/C, making me pretty certain its (somewhat) A/C related. It doesn't always show though, usually it start to happen after a few minutes and it feels more likely when I'm in slow traffic and/or using its Start/Stop system multiple times in a short period.

    No idea if this is new behaviour, as I've only been the owner of this car for about 8 months (and loving it, most of the time )

    Let me know what you think


    Last edited by smiba; 07-05-2019 at 11:12 PM. Reason: MPG UK converted to US, as its more used here

        __________________________________________

        click to view fuel log View my fuel log 2015 Space-Star 1.0 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


  2. #2
    Moderator inuvik's Avatar
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    Welcome to the forum! Glad to see another 1.0 owner on the forum. To answer your question indirectly although there is a noticeable power loss when the AC is engaged you shouldn't be taking that much of a MPG hit. One 1.0 owner posted information awhile back about some carbonization of the valves on his 1.0 but the consensus was that it was poor quality fuel. I'm sure others will chime in. Again, welcome!

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.4 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.5 mpg (Imp)


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    Have you owned since new? Could the compressor be starting to seize up?

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    Junior Member smiba's Avatar
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    I wonder.

    I've not owned this car since new and have actually never used the A/C before other then very short periods, I purchased this car when winter was approaching and only needed to actually use the A/C now.

    Any points I could check? I don't have a lot of practical experience working on cars mechanically but with the right instructions and tools I can try a bunch
    (I work in IT and Electronics Engineering)

        __________________________________________

        click to view fuel log View my fuel log 2015 Space-Star 1.0 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


  5. #5
    Where's the leak ma'am? Marklovski's Avatar
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    Hmm that does seem odd because the AC doesn't effect my fuel economy too much. My entire trip to and from the mountains was about 45 mpg (also consider my better tires and roof rack). I'd check if there's an AC leak.
    Fuel Log: Good enough
    Instagram: @zoras_sapphire

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    Junior Member smiba's Avatar
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    Yeah, it sounds very excessive. Thanks for noting your MPG with A/C on.

    What kind of AC leak would I be looking for? If it were to be the compressible gas I think I should be able to smell it, right? (The air out of the A/C smells just fine)

        __________________________________________

        click to view fuel log View my fuel log 2015 Space-Star 1.0 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


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    Senior Member Top_Fuel's Avatar
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    Running the AC in these cars is a mileage killer. It's a "feature" of the Mirage. Every time my AC compressor kicks on, it feels like someone threw an anchor out of my back window to drag along the ground.

    If you are on a fairly level road cruising at a steady 50 mph speed, the drag of the AC compressor may only reduce your mileage by 10% or so. But if you are running the AC regularly in stop and go traffic, or driving up a grade with it on, or driving 70 mph with it on...it is going to seriously impact your fuel economy. I have a ScanGauge that displays real-time instant MPG and you can watch the numbers drop significantly as soon as the AC compressor kicks on. These little engines are just not that efficient when under any sort of load. My guess is your 1.0 is even worse than the 1.2 we have here in the US.

    I never accelerate with my AC on. If I'm in a situation where I need to get up to speed, the first thing I do is press that snowflake button to turn the AC off. When I reach a cruising speed, I will turn it back on.

    How did something like a Geo Metro or an original VW Beetle ever have AC?!?

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 51.7 mpg (US) ... 22.0 km/L ... 4.5 L/100 km ... 62.1 mpg (Imp)


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    Senior Member Dirk Diggler's Avatar
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    Quote Originally Posted by Top_Fuel View Post
    Running the AC in these cars is a mileage killer. It's a "feature" of the Mirage. Every time my AC compressor kicks on, it feels like someone threw an anchor out of my back window to drag along the ground.

    If you are on a fairly level road cruising at a steady 50 mph speed, the drag of the AC compressor may only reduce your mileage by 10% or so. But if you are running the AC regularly in stop and go traffic, or driving up a grade with it on, or driving 70 mph with it on...it is going to seriously impact your fuel economy. I have a ScanGauge that displays real-time instant MPG and you can watch the numbers drop significantly as soon as the AC compressor kicks on. These little engines are just not that efficient when under any sort of load. My guess is your 1.0 is even worse than the 1.2 we have here in the US.

    I never accelerate with my AC on. If I'm in a situation where I need to get up to speed, the first thing I do is press that snowflake button to turn the AC off. When I reach a cruising speed, I will turn it back on.

    How did something like a Geo Metro or an original VW Beetle ever have AC?!?
    I must be missing something because I really dont feel that much of a difference with AC on or off. I see an mpg difference for sure but acceleration of the line, merging, etc I dont feel much of a difference. I know its nuts.

  9. #9
    Senior Member Cobrajet's Avatar
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    Quote Originally Posted by Top_Fuel View Post
    Running the AC in these cars is a mileage killer. It's a "feature" of the Mirage. Every time my AC compressor kicks on, it feels like someone threw an anchor out of my back window to drag along the ground.

    If you are on a fairly level road cruising at a steady 50 mph speed, the drag of the AC compressor may only reduce your mileage by 10% or so. But if you are running the AC regularly in stop and go traffic, or driving up a grade with it on, or driving 70 mph with it on...it is going to seriously impact your fuel economy. I have a ScanGauge that displays real-time instant MPG and you can watch the numbers drop significantly as soon as the AC compressor kicks on. These little engines are just not that efficient when under any sort of load. My guess is your 1.0 is even worse than the 1.2 we have here in the US.

    I never accelerate with my AC on. If I'm in a situation where I need to get up to speed, the first thing I do is press that snowflake button to turn the AC off. When I reach a cruising speed, I will turn it back on.

    How did something like a Geo Metro or an original VW Beetle ever have AC?!?
    /\ This. /\

    It seems like AC was a pretty rare option on Metros outside of 'The Sun Belt'. I hardly ever saw it on Metros here in the Pacific Northwest.

  10. #10
    Junior Member smiba's Avatar
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    Quote Originally Posted by Dirk Diggler View Post
    I must be missing something because I really dont feel that much of a difference with AC on or off. I see an mpg difference for sure but acceleration of the line, merging, etc I dont feel much of a difference. I know its nuts.
    I'm wondering, do you have your fan speed on low or on a higher speed (50%+ or more)?

    Today I needed to use the AC on my way back from work and noticed that using a low fan speed (lowest or near lowest) actually made the car feel much more responsive. (Didn't test it too much though, just drove home on the low fan speed) I was under the impression that the fans on high would at best use 20-50 Watts more and the AC would keep on using the same amount of energy (As its either on or off for the compressor wouldn't it be?)

    Anyways received my Scangauge2 this evening, maybe its just my driving behaviour that does allow me to drive efficient at normal engine load but doesn't work with the A/C also pulling power. I'll see if I can correct my behaviour or if its bad MPG either way.


        __________________________________________

        click to view fuel log View my fuel log 2015 Space-Star 1.0 manual: 48.8 mpg (US) ... 20.7 km/L ... 4.8 L/100 km ... 58.6 mpg (Imp)


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