# Fuel mileage change and acceleration issues



## snowwy66 (Nov 5, 2017)

What's the history on your oil changes?

I've only had my car 10 weeks and i've got half your mileage. My first tank of fuel netted me 33 mpg. I took to dealer after the first tank of gas. 400 miles for it's first oil change. MPG dropped to 28. And car was slower to cool down. I could park for 12 hours during the day at work. Come back and temp was still 120 degrees. 6 days days later i stopped at jiffy lube. Now i get 36 mpg and car cools down in a timely manner. Needless to say i won't be going back to dealer for the second oil change.


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## cyclewild (Aug 14, 2013)

Has the weather cooled signifigantly? I tend to take a pretty good mileage hit in the winter due to long warm-up times even while driving.


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## jblackburn (Apr 14, 2012)

Winter fuel, colder temps.

Failed oxygen sensors have been the most common issue with the Gen 2's.

If you're running 87 octane, try something higher. Acceleration jumpiness usually smooths out on 89-93.

Unfortunately, dealers will generally ignore your MPG concerns unless the car throws a CEL.


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## SilverCruzer (Nov 30, 2010)

The colder temps and winter fuel dropped my commute mpg from 46 to 40/41. Going from 40 to low 30's....something else is going on.

I have tried several tanks of higher octane gas without much noticeable difference in MPG or acceleration. I might be lucky, I don't know. Many others in this forum claim big improvements with the significantly more expensive gas.

Take look in the other threads. I recall reading how others found a loose hose connection of some type with those symptoms.


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## Bubs (Sep 13, 2017)

I havent seen a difference with different octanes. Everything looks in place. Should I start checking the turbo or spark plug gap? Anywhere I should be looking for leaks?


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## Bubs (Sep 13, 2017)

snowwy66 said:


> What's the history on your oil changes?
> 
> I've only had my car 10 weeks and i've got half your mileage. My first tank of fuel netted me 33 mpg. I took to dealer after the first tank of gas. 400 miles for it's first oil change. MPG dropped to 28. And car was slower to cool down. I could park for 12 hours during the day at work. Come back and temp was still 120 degrees. 6 days days later i stopped at jiffy lube. Now i get 36 mpg and car cools down in a timely manner. Needless to say i won't be going back to dealer for the second oil change.



Youre supposed to get a oil change after 400 miles? I dont remember seeing that anywhere.


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## jblackburn (Apr 14, 2012)

I did my first oil change @ 3000, then mostly by the OLM from there on (~7500).

I have seen a drop of 2-3 with colder temps, but nothing that significant either. Some people pre-heat their cars for long periods in the winter, and THAT can take a huge toll on fuel economy. You could also look for loose intake plumbing, particularly near the throttle body @ the back of the motor. That's happened to a few Gen 2's.


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## snowwy66 (Nov 5, 2017)

Bubs said:


> Youre supposed to get a oil change after 400 miles? I dont remember seeing that anywhere.


ALL my engines get changed at 500 miles. It don't matter if it's new or rebuilt. Car or motorcycle. I like flushing out the dust and whatever particles may end up being in the engine during assembly. 

The sticker said 2000 miles.


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## bcruze16 (Sep 30, 2017)

I had the same 2 problems with my 2016 Cruze, took it to the dealer and they laughed and said they couldn't do anything if there was no check engine light. Even called Chevrolet customer care who assured me they would take care of it. I've had the car for about a year and a half now, and nothing. No one bothered to look critically, no one took me seriously, but I know when these issues started. I used to get mid 40s, and now it rarely gets up to 40, most of the time I get 30-35mpg.

As far as the acceleration thing goes, it happens intermittently and didn't happen when the guy at the dealer drove with me. So as far as they're concerned, it's just my imagination.

Let me know if you ever make any discoveries. Would love to get my essentially new car working properly again--

best of luck!


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## snowwy66 (Nov 5, 2017)

Check back with us in the summer and let us know how things go. 

Winter performance has never been the same as summer for as far back as i can remember. 

Different fuel qualities. Colder thicker air. Thicker colder oil and transmission. And as @jblackburn mentions. Idle time. 

Semis usually drop at least 1 mpg.


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## jblackburn (Apr 14, 2012)

My last tank was 20 MPG. My average/fillups are in my signature below.

My car isn't broken. It's just trying to warm up in the EXTREMELY cold weather. I've been making liberal used of heated seats and remote start and doing short trips. Even coming back to the car 30 mins later, the engine has to repeat a lot of the warm-up.


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## Taxman (Aug 10, 2017)

jblackburn said:


> I've been making liberal used of heated seats and remote start and doing short trips.



Remote start is not compatible with high mpg. 
I wonder how many people remote start, repeat after 20 minutes, and then think there's something wrong with their car when they gas it up?

My boss lives about a mile from the office and makes liberal use of remote start on her Equinox. I bet she gets less than 15mpg on weeks she doesn't leave town.


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## jblackburn (Apr 14, 2012)

Taxman said:


> Remote start is not compatible with high mpg.
> I wonder how many people remote start, repeat after 20 minutes, and then think there's something wrong with their car when they gas it up?
> 
> My boss lives about a mile from the office and makes liberal use of remote start on her Equinox. I bet she gets less than 15mpg on weeks she doesn't leave town.


I never do it that long - remote start as I'm walking to it or 2-3 mins before. Enough to get the fuel pump to shut up a little bit and get fluids and stuff moving.


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