Last post on Sep 30, 2013 at 1:53 PM
You are in the Honda Civic
What is this discussion about?
Honda Civic, Fuel Efficiency (MPG)
#2004 of 2125 Re: AC's effect on acceleration and mileage [dantz]
Jun 23, 2009 (8:38 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 2125 Re: AC's effect on acceleration and mileage [thegraduate]
Jun 23, 2009 (10:56 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 2125 My first fill up - 2009 Civic LX-S
Jun 24, 2009 (12:34 am)
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 2125 Re: AC's effect on acceleration and mileage [dantz]
Jun 24, 2009 (2:20 am)
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 2125 2-3 MPG decrease with AC on
Jun 24, 2009 (3:22 am)
>"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.
#2009 of 2125 Re: 2-3 MPG decrease with AC on [kipk]
Jun 24, 2009 (6:30 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 2125 Re: 2-3 MPG decrease with AC on [ruking1]
Jun 24, 2009 (11:03 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.
#2011 of 2125 Re: 2-3 MPG decrease with AC on [kipk]
Jun 24, 2009 (11:11 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.
#2012 of 2125 Re: 2-3 MPG decrease with AC on [ruking1]
Jun 24, 2009 (11:18 am)
I was not in the room at the time but seems I heard on TV that VW is back with the Turbo Diesel, and it is getting super mileage. Seems they said 58 mpg. Is that possible?
#2013 of 2125 Re: 2-3 MPG decrease with AC on [kipk]
Jun 24, 2009 (11:28 am)
..."Seems they said 58 mpg. Is that possible?"...
I realize this is off topic, but the answer is yes.
I have done this across three states and a foreign country (had to count foreign country as I did a lot of stop and go driving and didn't buy fuel, as it was at least a $ more a gal than the US) , when three states (WA, OR, CA) had 5 highway patrol car wolf packs in full predatory mode (aka customer service) and the radar detector was going off so much, that it was just plain annoying. So I chose (03 VW Jetta TDI 5 spd manual) 75 mph with bursts to 80-85 and got 59 mpg (two fill ups) . NO TICKETS and I was surprised as anyone else, as I thought maybe... 55 mpg.
Further off topic, on a trip to Vancouver BC (2300 miles) the 09 Jetta TDI (DSG) posted 43.5 mpg overall during a herky jerky break in mode. A/C blasting, 3 folks, truck STUFFED to the gills. The GPS when it was on, said the car didn't exceed 90 mph. Torque is 115% greater than the below Civic. It also weighs 770#'s more.
More on topic, a 04 Civic posted 38-42 mpg on a R/T to Portland OR. A/C blasting, 2 drivers, two small overnight bags.