Summer is Here- Mileage Drop!

[ScooterS]

I've been clicking along with about 42 MPG. My C-Max mileage has been increasing since I got the car.

However, I live in Austin, TX and haven't had much really cold or hot weather.

 

Welllll...... Summer is here. I've noticed that my MPG is down about 4MPG from a couple of months ago over the last 2 tanks.  So what's the cause?

• I can attribute this to a few 80 MPH trips to the Airport (yes, that is the speed limit).
• There is less traffic on the road going to work since School (UT) is out. Thus, my inbound commute is less hybrid-friendly.
• Now that I have had the car for 6 Months, I've been giving my hybrid skills a bit less attention.  I could possibly save with a bit more  "pulse and glide."
• The A/C has been running full blast.  The good news is that It had plenty of power to cool the car within a few minutes on a 108 degree day.  The bad news is that I think this is the prime culprit on my MPG decrease.

 I suspect that the A/C is the prime culprit, but all are contributors.

 

Others.... What is you MPG experience with the summer heat??

Edited July 1, 2013 by ScooterS

[Recumpence]

One major secret is to run the ac at about 78 degrees. That will save you a lot of gas.

 

Matt

[mtb9153]

 

[HannahWCU]

One major secret is to run the ac at about 78 degrees. That will save you a lot of gas.

 

Matt

It really doesn't matter what the temperature is set at, what is important is to actually set it at a temperature. The compressor in the Cmax is a variable speed compressor. As the interior approaches the set temp, the compressor works less and leads. If you set it at "full blast" the compressor will consume the most power. Use the screen that shows the use of the AC (I don't remember the name of it).

[mtb9153]

I couldn't handle setting A/C temp to 78, maybe 76 or better yet 75.  I'm warm by nature so A/C is very important this time of year.  Blower speed must also have to be factored in as well?

[wamba2000]

Scooter, I am in AZ and have noticed the same thing.  My lifetime MPG was as high as 43.8, it is down to 43.2 as we speak.  My lifetime dropped to 43.3 when the dealer had it in for 3.5.1 and liftgate updates, hasn't gone up since.

 

Avg mpg per tank was running 46 or so in April, it is now around 41-42.  I have to attribute it to running the A/C and the 100+ temps every day in the past weeks.

 

BUT....we have to keep it in perspective.  I am driving a fun spacious car, loaded with all the toys, comfortable in 118 dgree temps and still getting over 40 mpg! I should count my blessings!

 

As to temp: I set at 76 and then nothc up once it cools....but when Mrs. Wamba is in the car, her side is down to 72 or 70, and I am usually freezing.  Oh well, happy wife, happy life!

[viajero]

 

Welllll...... Summer is here. I've noticed that my MPG is down about 4MPG from a couple of months ago over the last 2 tanks.  So what's the cause?

• I can attribute this to a few 80 MPH trips to the Airport (yes, that is the speed limit).

 

I drove that 80 mph toll road to COTA on Saturday.  I have a Scangauge and the instantaneous mpg was around 30.  That will certainly knock down your average.

[HannahWCU]

Run the AC at whatever you feel comfortable with, BUT if your interested in mpg, then set a temperature and let the car do what its designed for. Why is automatic climate control standard? To minimize the use of the compressor. Just my $0.02

[RachelnLa]

I don't like the auto ac. I found I get hot. Fast.

[FoutsNC]

Another thing that I have found that seems to make a large difference is setting the Recirculate to On.  If you are pulling air from outside, it can keep the compressor running on high even if it's fairly cool in the car.  I used to always keep the recirc off so that fresh air would come in.  I noticed a HUGE MPG difference when doing that.  Then I used the Energy guage to show the Climate usage and noticed a hugh drop in load just by switching it to recirculate.  It seems to default to recirculate when the AC is on, yet if you are turning that off, make sure you are aware of the load when doing so.

[HannahWCU]

Another thing that I have found that seems to make a large difference is setting the Recirculate to On. If you are pulling air from outside, it can keep the compressor running on high even if it's fairly cool in the car. I used to always keep the recirc off so that fresh air would come in. I noticed a HUGE MPG difference when doing that. Then I used the Energy guage to show the Climate usage and noticed a hugh drop in load just by switching it to recirculate. It seems to default to recirculate when the AC is on, yet if you are turning that off, make sure you are aware of the load when doing so.

I found this same thing. I want to be comfortable in my car. I start at 75, then as the energy gauge shows the AC use is a minimum, I start dropping my set point one degree at a time until I get to the temp I am comfortable at.

[plus 3 golfer]

One can monitor your climate use on the LH display.  You'll note that the use starts high to initially cool the car then settles on a fairly stable value. You can convert that average kW usage to kWh by the approximate time taken for the initial cool down and the time running after cooldown.  Convert the  kWh to BTUs and then BTUs to the equivalent fuel needed to run the engine (assuming an engine efficiency of maybe 35%.  Compare that number to your fuel used for the trip.  Everyones operating conditions will be different -- time, ambient temperature, humidity, set point temperature, number of stops where the interior heats up and so forth.

 

Also, remember that the AC runs whether the car is stopped, going 35 mph, or 80 mph. So, the % hit for running the AC will increase as ones overall FE increases (a greater portion of total fuel consumed will be used for AC as total fuel consumed decreases with increasing FE).

Edited July 2, 2013 by Plus 3 Golfer

[ScubaDadMiami]

I run the air conditioner 100 percent of the time, and I am still getting pretty good FE.  I set the temperature to 73F, have recirculate turned on, and then I vary between three to four bars on the power scale.  I do not use Auto, because that will turn off recirculate when the cabin reaches the set temperature.

 

It is over 91F during the day, and I leave my car parked in the hot sun.  So, it has some cooling down to do when I start my drive in at least one direction, daily.  I have my windows tinted, and I have Oxford White for my exterior color.  Oh, and I do close the shade for the panoramic glass while parked, but once the car has cooled enough, I open it to enjoy the light while driving.

 

I enjoy having fantastic fuel economy, but I simply must use the air conditioner at all times, and I just won't give up using it to the point where I am cooled off enough to enjoy the drive.

[Jus-A-CMax]

One major secret is to run the ac at about 78 degrees. That will save you a lot of gas.

 

Matt

I'll back that up as well ;)

 

Better than the 105 outside today and the car is still aerodynamic :drool:

[zhackwyatt]

Here in Phoenix it was 116 last weekend...I'm screwed.  I have to keep the A/C at 70 auto to keep from breaking a sweat and I use remote start so it just sits there for a few minutes sucking energy while it cools off.  I'll try the recirc trick, but on my commute I don't think it switches to outside air until half-way through anyways because the interior just hasn't been cooled off yet.

[Adair]

Wouldn't the outside air @ 116* defeat your purpose?

[zhackwyatt]

Wouldn't the outside air @ 116* defeat your purpose?

Yes, but I just never paid too close attention, and always kept it on Auto and let it do its thing.  The thing is, the temp inside the car is hotter than outside to begin w/, so I think you want outside air first and then switch to recirc once the interior is cooler than the exterior.  I'm not sure the A/C is that smart to do all that switching unfortunately--In fact, it does the opposite.

[fotomoto]

 I do not use Auto, because that will turn off recirculate when the cabin reaches the set temperature.

 

That hasn't been the case for me.  I use Auto about 90% of the time and the re-circ stays activated.  It seem only if I or more likely the wife change something that re-circ can sometimes disappear.  

Edited July 2, 2013 by fotomoto

[Edsel]

That hasn't been the case for me.  I use Auto about 90% of the time and the re-circ stays activated.  It seem only if I or more likely the wife change something that re-circ can sometimes disappear.  

 

Same here, my recirculation always stays on.

 

Edit*  Unless I change something.

 

Edited July 2, 2013 by Edsel

[zhackwyatt]

From the manual:

Note: When the system is in AUTO mode, and the interior and exterior
temperatures are high, the system automatically selects recirculated air
to maximize cooling of the interior. When the selected air temperature is
reached, the system automatically selects outside air.

[Edsel]

From the manual:

 

If it's doing that, it's all without the recirc symbol going off.(or maybe it is,I'll pay better attention next time)  I do notice a difference in smell when the desired temperature is reached/maintained. 

[zhackwyatt]

If it's doing that, it's all without the recirc symbol going off.(or maybe it is,I'll pay better attention next time)  I do notice a difference in smell when the desired temperature is reached/maintained. 

Right, the recirc symbol will only come on when you manually control it.  If you set the Auto up to 85 degress ,the hot air comes out the floor, but the floor symbol does not turn on.  In full auto mode, the system only shows ac/on or ac/off as an indication of what's going on.

 

Probably the easiest way to tell is after your system has finished cooling down and the Climate usage is minimal, change from recirc to not manually w/o making any other adjustments.  Recirc is generally louder.

[ScubaDadMiami]

The thing is, the temp inside the car is hotter than outside to begin w/, so I think you want outside air first and then switch to recirc once the interior is cooler than the exterior.

What I have sometimes done--and it actually works pretty well--is to use the fob to open the windows, as I approach the C-MAX.  I start up, and I start pulling away with all four windows open.  The wind will at least blast that hotter interior air out of the vehicle.

 

Within just ten seconds or less, I close the front windows only, not the back.  This lets the cool air coming out start to flow into the cabin while the back windows continue to let the last of the hotter air out.  I close the back windows perhaps five seconds after closing the front.  It is all a pretty quick thing designed just to get that hotter-than-outside air out.  Meanwhile, I leave the air conditioning on recirculate 100 percent of the time.

 

Leaving your air conditioning set to recirculate renders better fuel economy.  If you  are in a place that is hot, I see no sense in not doing this.  I like the added benefit of keeping fumes from other cars out of the cabin.  Of course, if you live in a place away from the city, this might not matter so much.

 

If you use auto start, I am sure that this doesn't kill your fuel economy by much, unless you let the car sit there for a while.  However, I have tried both methods, and I find that this is a good balance to getting the interior cool quickly while also not using fuel or battery.  Well, you do use a little battery power to open the windows, but that is not nearly as much as starting and running the air conditioner.

Edited July 3, 2013 by ScubaDadMiami

[salsaguy]

use A/C at 73 and use recirculate mode so it uses less power. turn on the dash display to show which accesories are using the power and how much to isolate. use max ac mode to cool it down with windows up, then switch to auto mode but with recirculate on.

Edited July 3, 2013 by salsaguy

[ScubaDadMiami]

I notice a big drop, right away, with Max.  I also notice a big drop with anything below 73 for the temp.  For me, it is all about fan speed. 

Edited July 3, 2013 by ScubaDadMiami