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Honda Civic Real World MPG

2058 messages,  Last post on Aug 26, 2009 at 6:19 PM

You are in the Honda Civic Forum. Your Hosts are pat & karens

What is this discussion about? Honda Civic, Fuel Efficiency (MPG)


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#2002 of 2058
Re: new Civic [mjsten] by thegraduate
Jun 15, 2009 (8:19 pm)
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Replying to: mjsten (Jun 15, 2009 12:12 pm)

I'd skip the hybrid assuming your 80hwy/20city won't change anytime soon. Hybrids shine in the city, diesels do GREAT on the highway.
#2003 of 2058
AC's effect on acceleration and mileage by dantz
Jun 23, 2009 (12:33 pm)
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Has anyone determined the Civic air conditioner's effect on both performance and mileage? Because I can't feel any difference in acceleration whether my 2008 Civic's AC is on or off. I realize that this model of Civic has a somewhat underpowered air conditioner, but it must also be remarkably efficient, as it seems to get the job done without any noticeable drag on the engine.
 
With my old Corolla I had the habit of temporarily turning the AC off whenever I needed an extra boost of power, for example on uphill freeway on-ramps, but with the Civic I can no longer tell the difference, so I just leave the AC on.
 
All I can think of is to do some test accelerations from zero to 60 with the AC both on and off to see if there is much difference in the elapsed time or the distance required. (I'll try doing this and then report back.)
 
I'd also be interested in knowing if anybody with a ScanGauge (or a similar device) has checked the instantaneous mileage in order to determine the AC's effect on highway mileage, while leaving the windows up. All I have found so far is comparisons between AC with windows up, and no AC with windows down, but that comparison is flawed because they are changing two elements at once. I think leaving the windows up and keeping the fan on while switching the AC on and off would be a fairer test.
#2004 of 2058
Re: AC's effect on acceleration and mileage [dantz] by thegraduate
Jun 23, 2009 (8:38 pm)
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Replying to: dantz (Jun 23, 2009 12:33 pm)

In almost any car these days (even my old '96 Honda), when the throttle is pushed hard, the A/C will momentarily cut-off on its own in order to channel more power to the wheels instead of the A/C. My dad's 2007 Civic is no different. On a hot day, get on the throttle hard while you feel the A/C blowing on your face. You'll feel a difference I'd bet.
 
Hope that helps.
#2005 of 2058
Re: AC's effect on acceleration and mileage [thegraduate] by dantz
Jun 23, 2009 (10:56 pm)
Reply

Replying to: thegraduate (Jun 23, 2009 8:38 pm)

Yes, I've considered that possibility, but as far as I can tell the AC appears to stay on and keep working during hard acceleration. But I'll test it again.
#2006 of 2058
My first fill up - 2009 Civic LX-S by bryan200k
Jun 24, 2009 (12:34 am)
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Bought my 2009 Civic LX-S just over a week ago. My first fill up was at 347 miles driven. 300 was Highway, 47 miles was City. Calculated MPG was 34.64 for first tank.
#2007 of 2058
Re: AC's effect on acceleration and mileage [dantz] by ras314
Jun 24, 2009 (2:20 am)
Reply

Replying to: dantz (Jun 23, 2009 12:33 pm)

I have a scan gauge and tried many times to determine the effect of the AC on mileage. Instantaneous mileage jumps around to much to make any comparison with AC on or off. Tried many times to run 10 miles over flat roads with no wind, still couldn't get conditions steady enough to see a noticeable difference with AC, Finally gave up and use the AC whenever I want. Maybe someone else has had better luck.
 
My mileage has slowly increased as I put more miles on, now around 18000 and haven't see a tank fill in some time less than 45 mpg. 2007 civic with manual, probably around 95% or more highway and lots of 55 mph roads. At interstate speeds mileage will drop to 40 mpg and even less with headwinds.
#2008 of 2058
2-3 MPG decrease with AC on by kipk
Jun 24, 2009 (3:22 am)
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>"I have a scan gauge and tried many times to determine the effect of the AC on mileage. Instantaneous mileage jumps around to much to make any comparison with AC on or off."
 
Using the Scan Gauge also, in our 03 4wd Pilot.. On a flat road or even going up a slight grade, with cruise on, the instant mpg will hold reasonably steady enough to turn the AC button on for a few seconds, and off for a few seconds. Mileage when the AC is turned on will drop "instantly" by 2-3 mpg. Then turning it off will increase the mileage by the same amount.
 
A 4 mile trip I take several times a week will typically return 2-3 mpg better with the AC off. That is starting with a cold engine. This spring, a 42 mile one way trip, I take often, yielded right at 27 mpg both directions. No AC. Cruise set at 58 mph for the X-Way portion.
 
Now that the temps are in the 90s and AC is on most of the time, the mileage has dropped to more in the 24-25 mpg range, at the same speeds. . I can keep it more in the 25 mpg range by "re circulating" the inside air and turning the AC on and off by hand.
 
Problem with Honda's Climate control is that if the AC is on, the compressor runs all the time. When the correct temperature is reached, the computer just adds heat to the system to maintain the correct temp. But the compressor continues to run.
Without Climate Control, and the "AC ON" condition, the Compressor continues to run and it just gets colder and colder. The driver can add some heat or turn the AC off.
 
Would seem to me to be better if the Compressor would turn on and off depending on whether or not more cooling is needed.
 
Kip
#2009 of 2058
Re: 2-3 MPG decrease with AC on [kipk] by ruking1
Jun 24, 2009 (6:30 am)
Reply

Replying to: kipk (Jun 24, 2009 3:22 am)

Actuall you guys with the scan gauge should try a different methodology.
 
Normally the A/C system takes app 15 min to stabilize.
 
Cycle the A/C ON. Put fan speed to #1. Regulate the coolness and leave it on.
 
When you turn it on and off you are making the system work harder to get UP and attempt to stabilize. This of course consumes more energy than the above situation which already has the system UP and stabilized and you are just twiking the temp to suit.
 
So anytime under that or cycling the system on and off will exact an mpg penality. Pass that, the system advances the timing slightly, takes little energy to stabilize the system and you should see pretty close to par for mpg.
#2010 of 2058
Re: 2-3 MPG decrease with AC on [ruking1] by kipk
Jun 24, 2009 (11:03 am)
Reply

Replying to: ruking1 (Jun 24, 2009 6:30 am)

I have tried it different ways, and the most efficient is using "Recirculate" as described above. When the "AC On" is displayed, the compressor runs continuously,
 
My wifes CR-V doesn't have Climate Control, so when it gets too cold we have the option of adding heat with the temperature control knob or turning the AC OFF and stopping the compressor. The Pilots Climate control automatically adds the heat when needed to maintain a selected temperature, but the compressor continues to run as long as that AC ON is showing. It will do that also in the winter.
 
The Pilot gets 2-3 mpg less when the Climate Control does all the controlling vs no AC at all. There is a 1-2 mpg difference when I use recirculate to cool the air and keep it inside the car.
 
Whether or not it is worth the hassle to turn the compressor on and off by hand depends on the frame of mind at the time. Not suggesting that anyone should do any certain thing. Just giving the facts as the Scan Gauge presents them. It is possible that turning the compressor on and off is hard on the compressor clutch, and that may be the reason Honda chooses to leave it running constantly.
 
Whatever their reason is, it cost me 2-3 MPG to run the air. So I just go with the flow and try to regain some of the mileage with driving techniques.
 
Kip
#2011 of 2058
Re: 2-3 MPG decrease with AC on [kipk] by ruking1
Jun 24, 2009 (11:11 am)
Reply

Replying to: kipk (Jun 24, 2009 11:03 am)

See, you have just done your fellow owners a favor.
 
Also I have a newer technology A/C (VW & not temp/climate) and it also works as I have mentioned. Honda at some point needs to switch to the more fuel saving A/C. But then again there is little incentive with folks buying them as they do.

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