[pi.actual]

AC has minimal impact on MPG in a HYBRID???

The engine need to be running in order for the AC compressor to work.
Therefore, AC is likely to have a similar negative impact on MPG as running the heat in cold weather.

Nope A/C is electric

 

[Bluegrass]

Nope A/C is electric

So won't the A/C draw power from the battery, causing the engine to run more frequently?

 

[HaulinAuss]

AC has minimal impact on MPG in a HYBRID???

The engine need to be running in order for the AC compressor to work.
Therefore, AC is likely to have a similar negative impact on MPG as running the heat in cold weather.

AC use in Hybrid may affect MPG more than ICE. I stand corrected.
Also read that driving with windows open may create more drag, thus reducing MPG.
In any case, I run the AC whenever needed (more than 50% of the time) and MPG is still good.

 

[tc0566]

I don't think AC is affecting it much. I drove 140 miles to Mentor and back from Canton Ohio Sunday with AC on. My hatch got 50mpg and 98% of that trip was on the highway at 70mph.

 

[Symphonic89]

AC has minimal impact on MPG in a HYBRID???

The engine need to be running in order for the AC compressor to work.
Therefore, AC is likely to have a similar negative impact on MPG as running the heat in cold weather.

Honda hybrids have an electric powered compressor. Mine stays in EV mode just fine with the A/C on.

 

[pi.actual]

So won't the A/C draw power from the battery, causing the engine to run more frequently?

After 10k miles it doesn't seem to have much effect and I have it in AUTO at 70 deg all the time. I'm sure it has some effect just as it does with a normal car but in this car it seems that heat causes a much bigger hit.

 

[Bluegrass]

Honda hybrids have an electric powered compressor. Mine stays in EV mode just fine with the A/C on.

The "electric powered compressor" obviously draws power from the battery, which means the gas engine must turn on more frequently to replenish the power it is consuming, thus lowering fuel economy.

 

[Bluegrass]

The last few posters are quoting fuel economy figures based on the vehicles trip computer, which has been documented to be inaccurately optimistic, so you'll need to knock 2-5 MPG off those claimed numbers.

This also doesn't answer the question I posed, which is how much impact AC usage has on fuel economy, since we know for a fact using AC will reduce fuel economy.

 

[TailWagger]

Total stab in the dark, but a quick search of the internet suggests that electric ACs consume somewhere between 1.5 - 3 KWH. So worst case it takes fully recharging the 1.1 KW battery ~3 times per hour. I cant find anything related to miles per KW figures for Civic, but anecdotally, I see two or three bars used to travel ~1/2 mile in EV at around 40 MPH. Admittedly very loose guess, but lets say its somewhere between 2-3 Mpkw, which seem plausible (I regularly see between 2.8-3.5 from my 330e).

Assuming any of the above is close to correct, worst case would be using 3.3Kw for AC vs using it for going down the road, so somewhere around 10 miles of range per hour (avg somewhere around 40MPH). Presumably the faster you go, the less this impacts (as a percentage) your fuel economy, certainly at 70+ far less than open windows would.

 

[HaulinAuss]

The last few posters are quoting fuel economy figures based on the vehicles trip computer, which has been documented to be inaccurately optimistic, so you'll need to knock 2-5 MPG off those claimed numbers.

This also doesn't answer the question I posed, which is how much impact AC usage has on fuel economy, since we know for a fact using AC will reduce fuel economy.

1. AC impact on fuel economy? There is no one answer as the impact will vary based on a variety of conditions. (I do get better mileage in warm temps with AC on than in cold temps with AC off). 2. Based on the last 3 fillups, my trip computer is inaccurate (overly optimistic), by 2 to 3 MPG. MPG is still within the EPA estimates however. 3. I cannot say the same about our 2024 Hyundai Tucson Hybrid. I'm now convinced it will never reach the 37 MPG estimate. I'll be lucky to get 31 MPG.

 

[Symphonic89]

The "electric powered compressor" obviously draws power from the battery, which means the gas engine must turn on more frequently to replenish the power it is consuming, thus lowering fuel economy.

I was simply addressing your statement that "The engine need to be running in order for the AC compressor to work", which is false.

 

[Nouseformonkeys]

When I bought my Hybrid Sport Touring at then end of 2024, I was getting mpg in the low 50s. Now that the temperatures have heated up and we’re running the AC more, I’m getting in the mid 40s.

 

[Derrick]

When I bought my Hybrid Sport Touring at then end of 2024, I was getting mpg in the low 50s. Now that the temperatures have heated up and we’re running the AC more, I’m getting in the mid 40s.

Those are great data points, but what temps are you talking about? If first MPG was during 70’s and second lower MPG was during 90’s, it could also be the fact that battery inefficiency increases with very hot (and very cold) outside temps. It’s not just about the AC.

 

[Nouseformonkeys]

Those are great data points, but what temps are you talking about? If first MPG was during 70’s and second lower MPG was during 90’s, it could also be the fact that battery inefficiency increases with very hot (and very cold) outside temps. It’s not just about the AC.

Good point. And yes, in the early months of 2025, the temps were in the upper 70s and low 80s. In May the temps are in the upper 80s and lower 90s. Mostly around town driving with a few highway trips.

I’ve been in Normal mode 99% of the time. During the cooler months the AC is on low. In the hotter months, the AC is set on blast until the cabin cools down and then it goes down to 2 or 3. I couldn’t make the mental shift to use the Auto mode. Lol.

 

[Maddman]

Just returned from a two day trip from Des Moines Iowa to the Mayo Clinic. The route was 225 miles each way. Speed was between 70 and 75 on the highway or 5 over in slower areas. Going up I got just over 42mpg. Coming back the average was 50.1mpg. Around town (mix of highway and city) its getting 50+mpg.

Mileage drops like a stone when it is cold which is why I am looking at adding a block heater for the winter months.

 

[Derrick]

A lot of it is the battery affecting mileage in the winter, not just the ICE/heater.

 

[1000FC]

it will be interesting to see what peoples MPGs are after a full year.

currently at a lifetime avg mpg of 45.673 with 11,450 mile

with my lowest MPG for a tank being 31.4 (during a very cold spell in February), highest was my penultimate tank: 53.46

bought the car beginning of October.

 

[HaulinAuss]

A lot of it is the battery affecting mileage in the winter, not just the ICE/heater.

The primary reason MPG tends to be lower in the winter is the ICE must run for longer periods of time. And, of course, the longer the ICE runs, the more fuel consumed.

 

[kart17]

For data purposes worth nothing what modes people are using primarily to see if there's a difference as well..

 

[Hatch808]

This is wrong.
The EPA does NOT "do the testing to provide the numbers on the window sticker".
The actual testing is done by the vehicle manufacturer, supposedly per the EPA's standards.

Yes and the EPA verifies metrics via spot testing.

I recall awhile ago Hyundai/Kia got caught boosting their MPGs.

Supposedly the EPA prioritizes spot testing of cars that have higher claimed MPG or new technology or if there are lots of consumer complaints.