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MPG has dropped over the summer

11K views 31 replies 13 participants last post by  Ann Von Hagel 
#1 ·
2018 HEV here. I kept reading how everyone was saying that their MPG got better in warmer weather compared to winter time. Well, the opposite has happened with my Niro.

In the winter and early spring my Niro was averaging 52-58 mpg around town and 42-46 mpg on the highway.

Now that summer is really here now, city mpg has dropped considerably but highway mpg has stayed the same. City mpg has dropped from 52-58 to 42-46 mpg!!

My tire pressure is good at 37-38 psi. Got an oil change done last month and it did not change the mpg. It now has approximately 17,500 miles on it now after 7 months of ownership.

Now, I do always have the A/C maxed out at all times due to living in Texas with 100+ degree days, 70+ degree dew points, and my Niro is black as well.


So am I the only one who’s mileage has dropped during summer?
 
#5 · (Edited)
91CAVGT- when you are using A/C, do you put it on driver only if just you driving; and do you have the fan on max or near max speed? I have found that makes a difference in MPG over that used running on just driver at ~3 fan speed. When running like this, the MPG cost is not much, certainly less than the old belt driven A/C's. Maybe even less than running with windows open. I run mine nearly all the time in summer also, temps currently in upper 80's-low 90's.
 
#8 ·
I guess that's true in that it will make the air cooler so you can turn the fan lower, otherwise I don't know why it would reduce energy. The A/C comp pump is running at a set speed, if you have it running all the time it doesn't know if you have it on recirc or not. Except the fan works a little better when it's not pushing through a filter.
 
#11 ·
I don't run at auto temperature, because I've seen it put out warmer air to remain at set temp, and vice-versa for auto heat temp. I run mine all the way down to low, and adjust by fan speed. If you make an auto set temp, and it's near that point, it won't run any more efficiently by running warmer, because that mix is controlled at the heater core. The air compressor just knows run.
 
#13 ·
This morning I drove to work at 7 am and the car showed an outside temp of 82 degrees. So for the first time in a while I drove to work with my windows down. The mpg this morning averaged 62 mpg.


When I drove in the afternoon, I have the A/C maxed out with recirc on. It stays that way for the entire time I’m driving. Even if I set it to automatic, it never drops off of fully maxed out. In my opinion, with where I live, it seems like the A/C is sized a bit too small. But, during the summer it is normal to have temps into the low 100’s with dew points in the low 70’s. Not only that, but my car is black which makes a big difference.
 
#22 ·
In my opinion, with where I live, it seems like the A/C is sized a bit too small. But, during the summer it is normal to have temps into the low 100’s with dew points in the low 70’s. Not only that, but my car is black which makes a big difference.

The AC on our Prius AC was different and got cool air MUCH quicker than the Kia. Once we get going it seems to manage OK at laest for the front seats (we are only two people). I also live in Texas and this year is hotter than I remember previous years being, 100 or over day after day after... For parking during the day outside, I've also dug out the windshield reflectors and when I park put them on and set the sunroof to tilt with the cover cracked and crack both front windows a little. The car interior is now more like outside rather than EKKK! I need oven gloves to drive this thing!

The worst AC unit was a small Honda we had. Not hybrid. Just a car with way too small an AC for Texas!
 
#14 ·
You forgot your punch line - the afternoon drive with AC mpg!

Exterior color of the car doesn't impact the interior temperature as much as you think, although you can find evidence either way. More important is the amount of glass, and the tint. Dark interior colors likely make your interior hotter, but this too is controversial.
 
#18 ·
I have not tracked MPG with the amp on or off. It just isn’t that high up on my list of concerns, and I too love my music!


So on my trip back home, ambient air temps started off at 102 degrees and got as high as 104 degrees!! That’s hot!! So the end MPG ended up being 37.8 mpg.
 
#19 ·
The curves on engine efficiency I've seen show a peak at near 85 degrees, dropping off with higher temperatures. AC use would further diminish the peak efficiency you saw in the morning at 82 degrees with no AC. Check also your starting and ending altitude - that can make a significant difference in each trip's efficiency. Assume you were keeping the same speed both ways of course. Starting battery charge also makes a difference.
 
#23 ·
I got a 2017 Niro in May 2017. I live in NE. There are times in nice weather, w/o running AC or heat, I average as low at 28 mph, especially on longer drives. My first couple months I was getting 46-50 mpg. Then it changed in Sept. I started complaining 3 months after I bought it. They came up w/every excuse under the book: cheap gas, wind, hills, my driving, using cruise, not using cruise, driving over 55 mph. You name it, I heard it. I kept complaining with each oil change. “I’m reading Niro drivers in Wisconsin in winter with hills driving 75+ getting over 50. You promised me 49/51.” They asked me to keep track of my mileage and gas. So I did. They asked me to buy premium, so I did. They asked me for screenshot stories of these great mpg stories. So I did. The ONLY reason I purchased this Niro was the promise of 49 - 51 mpg in NE with regular gas. Kia finally did a 3 day long series of analysis/tests. Their results were the same as mine. Yes, driving under 55 mph does increase the mpg. But I drive 60 miles each way almost all interstate, 5 days a week. The typical speed on I80 for this stretch is 82-85 mph. No way can I drive 55 mph to get closer to their mpg Kia claimed, advertised and promised. Kia explained there are so many variables and that even in nice weather, I should expect 37-38 mpg on my interstate drive. And much less in winter. I was livid. If that’s the case, then Kia shouldn’t promise 49/51. Such a bait and switch. Felt like I’d been lied to. Then, over two years later, I’m finding improved mpg. 44-50 this summer, with hills, wind, driving 80 mph, ac on both sides, ethanol gas. It’s like after passing 55,000 miles/odometer, it finally started delivering near its promise. Still, I endured 2 years of disappointments, every excuse in the book, and much experimenting in how I drive, my speed, AC, heat, tires, cruise, etc. I have no idea if this better mileage will continue as the weather changes, but for now, I’m happier. However, next time around, I’ll be driving a Prius.
 
#26 ·
I'm not sure if you've owned a Prius before but as someone who owned several since 2004 I can say that you'll see the same thing happen with a Prius. In fact I'm very happy that my Niro gets about 2 mpg's better than my old 2012 Prius. I think when you watch your mpg's TOO closely you'll see some unexplained things that will make you nuts. My old Prius would generally get around 45mpg's when we lived in Pa. Sometimes after an oil change the mpg's would inexplicably go down in the high 30's. I would think the dealers used the wrong weight oil only in a few weeks the mpg's would go back up without any changes. Same when getting new tires. Sometimes mpg's would go down when you think they should go up and then in a few weeks go back to normal all by itself. So far my Niro hasn't shown any of this but it's still new (17,000 mi.) versus my last Prius had 166,000) when I traded it. I think you can't watch the mpg's super close, it'll make you crazy LOL.
 
#24 ·
Really? You expect 50 mpg driving over 80 mph? I'd be pretty happy to get 40 mpg at those speeds. You do know the EPA doesn't run at 80 mph to get their relative mpg figures?

I do have to say 28 mpg is low! But we have no idea where that number came from. Was it on the dash display after a 10 mile run in a headwind at 80 mph at zero degrees? Or was it a full tank where you calculated the mpg?
 
#27 ·
I'd say about 75-80F to be optimum temp for a Niro, at least mine seems to be. My 04 TDI it would have been about 65-70F. MOMWITHANIRO get yourself some sort of TDI and do 75-80mph and get about 44mpg winter or summer and hammering it passing and whatnot. Or get a Tesla if you can swing it, but a hybrid is the wrong choice for your type of commute. Trips under 5 miles are also devastating to miles per gallon especially in the winter. Two mile trip to Shop-Rite on a 10F day and you'll be lucky to get 28mpg.
To a lesser extent goes high temps. If your winter temps are in the 50s-60s then sure your winter mpg will be better. At over 100 degrees the battery efficiencies drop. The cooling system is running like mad(the other coolant reservoir) to keep the battery from melting. In Texas you're doing 85 in the slow Lane and with those dewpoints it's hard for any a/c to keep up.

As for losing mpg after an oil change I think you're gas tank is being poached and I'll double down on that bet if it's the same place you get tires.
 
#28 ·
Update;

Since coming back to work from our summer break (I am a school bus driver), I have been driving with the A/C off and the windows open. I have been doing that because the A/C in my bus never cools the bus down when outside temps are over 85 degrees, and I get bad headaches by going in and out of air conditioned environments.

Currently after 47 miles on this tank of fuel, it is sitting at 66.4 mpg. This is with an ambient temp in the shade right now of 100 degrees. It just seems like, in this environment, running the A/C is a VERY large power drain.

Ohhh, I have also been driving around with my stereo cranked up too. On Friday I put my meter on my amplifier and it was putting out 53 volts of AC current at 2 ohms. That is a hair over 500 watts of power.
 
#29 ·
Wow thats a big difference but there is no way I would do without the A/c I'm in Memphis pretty warm here too. But I'm at about 45 mpg with my Fuelly mostly highway miles so just about what Kia says I'll get so I'm happy. But I'm adding some Chevron Techron soon just for an experiment if it gets any better.

I usually kick A/c on high because its scorching hot for a few minutes then cut it down on 3 or 4 during the day. This is drivers only and set on low temp.
 
#30 ·
I just drove my PHEV over the mountains and back today. Obviously I didn't get much help from the battery range. The MPG for the entire trip was a hair over 50 MPG. But that was crossing two different mountain passes (one lower than the other) in both directions. That kind of mileage, over mountains, at freeway speeds, and HVAC on, is more than satisfying.
 
#31 ·
95 miles on the tank now and 62 mpg average. Had to go wash the car, then drive on the highway to dry it off, with the windows up so I had the A/C on max. That explains the drop in average fuel economy.


When I left my house an hour ago to come back to work, my car was showing 104 degree ambient temp. It’s HOT!!!
 
#32 ·
We've had ours for just over a year and a half -- mileage is best when outside temps are 'comfortable'. So very cold and the mpg dips -- even without using the seat and steering wheel heaters. Also dips if temps are quite high, though not as badly as in the winter. Note, I've not done any 'laboratory quality' data collection or analysis; that's just my impression. :)
 
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