[fernandocolon]

Nice - your fuel efficiency should be amazing then! If you read some of the recent "MPG" postings, we're just recently starting to warm up to ~68F in the US; today is the first day of spring. U.S. winter temperatures were 32F and below. The cold temperature can cause a 10+ mpg difference over the same route, especially since the gas engine runs to warm up the cabin and recharge battery for other cold-weather accessories.

I think the a/c does the same damage to MPGs as the heater does. In the mornings when the temperature is at 72-74 , take my kid to school and got consistently 52 MPG. In the afternoon when the temperature is 89-92 , the same drive and I'm getting 43-44 MPGs. I'll keep investigating

 

[hasarad]

I think the a/c does the same damage to MPGs as the heater does. In the mornings when the temperature is at 72-74 , take my kid to school and got consistently 52 MPG. In the afternoon when the temperature is 89-92 , the same drive and I'm getting 43-44 MPGs. I'll keep investigating

Believe it or not, the A/C isn't as bad as the heat. At least, that's my observation from last summer. Heat kicks in the ICE when the coolant temp drops below a certain level. A/C uses battery that's available. It may sound similar, but battery is more avaialble in summer when A/C is used vs. the ICE.

 

[Mobilcams]

Living in Florida I’ve noticed when it’s warm, the first 10 minutes of driving (so far) the ac does use a little more battery in city driving and fuel economy is hurt a little, after that it’s not really an issue. What I do LOVE is the fact that I no longer can tell I’m running the ac like I could in my civic or my girlfriends corolla when it comes to accelerating quickly. No drag from the ac compressor. Also one of my former Civics was a 2008 hybrid with a hybrid electric/mechanical ac compressor that went out at 110,000 miles (very expensive repair). Drove the last two years I had her without ac in Florida. The fact that this system is fully electric actually gives me hope that it will hold out for a longer amount of time.

 

[Mobilcams]

Here's something of interest to note. I have my daily commute of 50 miles each way going to work and home. Here in Florida it's been pretty darn hot. What I have noticed is that your AC settings can have a huge impact on MPG. I like to get fresh air in through the vents so I turn off recirculate quite often. I have noticed when I do this, running at 70mph my MPG will drop to around 44mpg. When I leave it in auto and recirculation is enabled it shoots up to 48 - 50. Food for thought. Makes sense to me.

 

[Wifey'sInsight]

Here's something of interest to note. I have my daily commute of 50 miles each way going to work and home. Here in Florida it's been pretty darn hot. What I have noticed is that your AC settings can have a huge impact on MPG. I like to get fresh air in through the vents so I turn off recirculate quite often. I have noticed when I do this, running at 70mph my MPG will drop to around 44mpg. When I leave it in auto and recirculation is enabled it shoots up to 48 - 50. Food for thought. Makes sense to me.

I've been pondering posts like this over the past week, I'm going to go out on a limb and say the reason why eco mode prefers re-circulate has something to do thermal dynamics.

I find it interesting that the insight doesn't have active grill shutters (I assumed it did). So instead of an aerodynamic change that I had assumed, I now believe it prefers re-circulation because it's easier to cool already cooled air, than fresh warm, and potentially humid air.

 

[andrew28]

It's also nice that AC recirculate prevents exhaust fumes from the vehicle in front coming inside the cabin.

 

[808_Insight]

I will say that running the A/C on this 2019 has far less effect on mpg than it did on my 2010 Insight.
It does appear to deplete your batterie's charge quickly if the ICE isn't running (in Traffic, etc) but much improved over the older model. On this SF trip, I did run the A/C set at 74.

 

[andrew28]

I have noticed that everyone seems to have AC temp set at different ranges (mine is at 60 or lo). Does the colder ranges impact fuel economy more and also does AC temp matter if you have AC recirculating the same cold air?

 

[insightfully]

I have noticed that everyone seems to have AC temp set at different ranges (mine is at 60 or lo). Does the colder ranges impact fuel economy more and also does AC temp matter if you have AC recirculating the same cold air?

While it may not be an apples-to-apples comparison from an absolute energy measure, I think of managing car temperature like home temperature.

• For homes, the 'professional' reco is to run the thermostat low in winter and high in summer to minimize energy use. Home energy services quote 2-5% extra cost in winter (or savings in summer) electric bill for every degree of temperature raised on thermostat. It's harder to quantify the actual energy used by the Insight's electric motor to supply A/C, but I think the directional energy principle is similar.
• Another conceptual rule-of-thumb from home heating/cooling thermodynamics is that A/C is more efficient and uses the least net energy when run for a short time at full blast, rather than running constantly at a low setting. The rate of cooling output from the A/C is constant, so the system has to run longer (use more energy) to get to and maintain a lower temperature setpoint of 60F vs 74F.

A/C energy use relates to the difference in current temperature to target temperature (thermal gradient). Even after the car is cooled to 60F and has recirculation running, there was 'extra' A/C energy used to get the car to 60F vs 74F, plus more A/C energy used to maintain the 60F (assuming the outside temperature is >60F). How much more actual energy is used between these temperature scenarios might best be quantified by someone with an OBD meter, maybe measuring/monitoring battery charge -?

 

[Wifey'sInsight]

I couldn't have said it better than Insightfully, and I'd also add that a/c is traditionally more efficient than driving with the windows down. I'm sure this is more true with our platform, especially at 45+mph.

My general approach is setting the a/c at 68, or within 2-3 degrees of ambient temperature. For example this morning was a very humid 60*, so the a/c was set to 63. The major benefit is that a/c (and heat) removes excess humidity from the air.

 

[andrew28]

While it may not be an apples-to-apples comparison from an absolute energy measure, I think of managing car temperature like home temperature.

• For homes, the 'professional' reco is to run the thermostat low in winter and high in summer to minimize energy use. Home energy services quote 2-5% extra cost in winter (or savings in summer) electric bill for every degree of temperature raised on thermostat. It's harder to quantify the actual energy used by the Insight's electric motor to supply A/C, but I think the directional energy principle is similar.
• Another conceptual rule-of-thumb from home heating/cooling thermodynamics is that A/C is more efficient and uses the least net energy when run for a short time at full blast, rather than running constantly at a low setting. The rate of cooling output from the A/C is constant, so the system has to run longer (use more energy) to get to and maintain a lower temperature setpoint of 60F vs 74F.

A/C energy use relates to the difference in current temperature to target temperature (thermal gradient). Even after the car is cooled to 60F and has recirculation running, there was 'extra' A/C energy used to get the car to 60F vs 74F, plus more A/C energy used to maintain the 60F (assuming the outside temperature is >60F). How much more actual energy is used between these temperature scenarios might best be quantified by someone with an OBD meter, maybe measuring/monitoring battery charge -?

I was leaning towards the same idea that having the AC temperature range being at the low end will use more energy. The information you have provided does make sense for what I'm seeing with my Insight. I had the AC temp range higher during May(fuel economy impact not noticeable) but now in June I have it lower where I do notice a decrease of around 3MPGs.

I couldn't have said it better than Insightfully, and I'd also add that a/c is traditionally more efficient than driving with the windows down. I'm sure this is more true with our platform, especially at 45+mph.


My general approach is setting the a/c at 68, or within 2-3 degrees of ambient temperature. For example this morning was a very humid 60*, so the a/c was set to 63. The major benefit is that a/c (and heat) removes excess humidity from the air.

I have been driving with windows up, to keep the bugs, and dust out of the cabin. Had a spider crawled in through my driver side window while I was driving a few weeks ago. Thanks for the tip on setting the AC temperature range. It should help with energy efficiency while getting rid of the humidity(I don't mind the heat most of the time just the humidity:grin.

 

[pasei]

Used the AC for the first time yesterday, pretty impressive! I measured the outlet air was at 32°F, which is the minimum an AC system can go. Whisper quiet... Lost about one bar of battery in something like 3 minutes (at full blast).

 

[hasarad]

I turned mine on last night. My daughter turned it off a few minutes later because she was cold. Wuss...

 

[pasei]

82.4mpg: no AC

65.5mpg: AC at 68°F (with hot cabin) + charging phone @ 4A (so 20W, probably irrelevant)

74.4mpg: AC at 72°F

That's on my suburban test loop. Outside temp: 80°F.