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Discussion Starter #1 (Edited)
First, I did search and read. Second, I'm not officially a mechanic, but I could tear this car down and rebuilt it if I had to, and I'm somewhat fluent in car ;)

Ok, so I have a '15 cruze eco 6mt that I like a lot. It's got just over 1,000 miles now. So far for the 3 tanks I've driven I've averaged right around 37 mpg. I've gotten the 25 and 50 mile averages up to 48.4 and 45.5 respectively, which is the best I've done so far. I live in the country and it's relatively hilly, and I have done some highway miles on my daily commute.

Anyways, I've noticed the car has some issues with losing power and it just occurred to me today, that perhaps since I'm running 87, it's pulling timing to avoid knock. My research indicates that is very likely, so I already ordered a bluetooth obd2 adapter and will use an app to track that sort of stuff. That said I have several questions;

-will torque or any of the other Android apps show me if it's pulling timing?
-will I get better mpg on 89 or up octane? Is 89 enough to avoid timing being pulled on a hot day with ac on and 5 people in the car? ;)
-is 37 mpg good for mixed hilly driving (minimal stop and go)

On a side note, just fyi, there are no tunes in the future for this car, as much as I'd like to (and the prevalence of e85 in my area), the dealer I bought from offers a lifetime power train warranty that I'd like to not void.

Also, I just thought I'd let you kids know, the nicest car I've owned prior is an 01 BMW 330i sport. The cruze is close quiet wise, it's similar smoothness wise, the brakes aren't quite as powerful but they're not dramatically worse, and it corners a lot closer than I expected. (Especially factoring in the bmw has 225/xx/17 front and 245/xx/17 rear performance tires). I like the cruze more personally, even if it is wrong wheel drive.
 

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With 91 or 93 octane you will see a +/-10% increase in mileage and your loss of power issues will improve. Fuel for the cruze is recommended at 91 octane. Where I live not all stations have 91. Most have 92 or 93 and I've been using 93 lately and like the noticeable improvement in performance. Stations here go from 87,89,92 or 93 so I use 93 instead of 89. For warm/hot weather I would definitly use 92/93.

I don't know anything about the apps but I would just use higher octane and be done with it. 37mpg is good mileage for your driving and it will improve with higher octane. I have a '13 cruze with 10k miles and have averaged 37.3mpg so far on 80/20 highway/city driving. Since I started using 93, MPG is about 43.
 

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Discussion Starter #3
One other thought I'd like to add, would it be effective mpg and or octane wise to just run 1 gallon of e85 with the rest 87. E85 is literally all over the place around here and I live 15 minutes from one station.

If no one is sure I might try it out of curiosity.
 

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You could try the E85 mix but there is the potental of a check engine light.
If the computer can't enrich the fuel mixture enouph to compensate for the additional oxygenate it sets a lean code.

Try mid grade for a couple of tanks, then try premium for a couple.
I and others have found significantly better driveability in hot weather by using the higher grads and yes, you are correct, the car pulls timing rather aggressively if it sees any knock.
When temperatures drop to 60f and less I see no difference in performance or mileage improvement....so my winter fuel is regular.

Congrats on the new ride!
Rob
 

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I have a 14 Eco 6 speed, have only used 87 octane and I have 12k miles, I use top tier gas, have a lifetime average of 40 mpg on the car display. Car runs great and has exceeded my expectations. Your car probably isn't even broken in yet. I have thought about putting in pure gas here and it is 91 octane but it's like 40 cents more a gallon.
 

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Discussion Starter #6
Thanks, and yes, I've noticed it during the day when it's 85-85-95 with the ac.

I work at night so I've noticed it's gone when it's 65-75 without ac.

I originally thought the car just struggled with the AC on that much (you know, 3,000lb car, 1.4 motor). But like I said, the timing thing occurred to me yesterday.
 

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I have the 14 Eco 6 speed, in the owners manual it says in section 9-52 use 87 octane and if get knocking to use higher octane. It also states to use top tier gasoline. Perhaps the older models were designed for higher octane but not 14 or newer. My 14 has never knocked one time on 87 octane. I have also driven the car in the mountains. So saying the manufacture says 91 octane on a 14 or 15 Cruze is just inaccurate.
 

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Discussion Starter #8 (Edited)
I have the 14 Eco 6 speed, in the owners manual it says in section 9-52 use 87 octane and if get knocking to use higher octane. It also states to use top tier gasoline. Perhaps the older models were designed for higher octane but not 14 or newer. My 14 has never knocked one time on 87 octane. I have also driven the car in the mountains. So saying the manufacture says 91 octane on a 14 or 15 Cruze is just inaccurate.
I didn't look in the owners manual, however, in my searching a discussion was had about the rpo codes and krd meaning it's meant for 91 octane. Mine does have krd in the codes btw

I can tell you though for sure, that my '15 feels like it's losing timing bad
 

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I didn't look in the owners manual, however, in my searching a discussion was had about the rpo codes and krd meaning it's meant for 91 octane. Mine does have krd in the codes btw

I can tell you though for sure, that my '15 feels like it's losing timing bad
Maybe there is a problem with your car and should be taken to your dealer. I have never had 5 people in my car either. The back seat is only meant for small children in my view. I haven't tried higher octane but have been happy with the way my car drives and performs so why spend the extra $$$. Hope you get it figured out.
 

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I can tell you though for sure, that my '15 feels like it's losing timing bad
Have heard rumors that 2014+ cruze run much better on 87 octane than the 2011-2013 models do, but I can't see any tune changes defying the laws of physics. When its above 80F outside your car will run much better on premium than on regular fuel.

I only run premium now, with the MPG increase I see plus seeming to have a bit more power sounds like a win win to me.
 

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Maybe there is a problem with your car and should be taken to your dealer. I have never had 5 people in my car either. The back seat is only meant for small children in my view. I haven't tried higher octane but have been happy with the way my car drives and performs so why spend the extra $$$. Hope you get it figured out.
That discussion may have been applicable to earlier models. If the owners manual says 87 that should be a better source in my opinion that some online discussion
 

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Honestly just run 93 octane all the time, there's no reason not to. If you can't afford 30-40 cents more per gallon, then you shouldn't of bought a brand new car...no offense. You get better mileage and more power. The car just drives much better on 93, especially when using AC and or have extra people in the car.
 

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Honestly just run 93 octane all the time, there's no reason not to. If you can't afford 30-40 cents more per gallon, then you shouldn't of bought a brand new car...no offense. You get better mileage and more power. The car just drives much better on 93, especially when using AC and or have extra people in the car.
I can afford to drive any car I want, putting 93 octane in a economy car is a waste of money. If it was needed it would be in the owners manual.
 

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I can afford to drive any car I want, putting 93 octane in a economy car is a waste of money. If it was needed it would be in the owners manual.
You obviously already have your mind made up, even thought here is more more than enough evidence that these 1.4T engines run better and get better MPG on premium fuel. In my hilly route, I pick up 2-3mpg running premium, which does make up for some of the extra cost. Turbo engines run hotter naturally so in the summer heat will achieve better MPG on premium. The Ultimate Hot Weather MPG Test - Regular vs. Premium - 2011 Chevrolet Cruze LTZ Long-Term Road Test

1. The same engine in Europe requires premium grade fuel
2. The RPO code list in glove box indicates 91 octane fuel
3. The 2015 owners manual actually says on 9-51 "Use regular gasoline with a posted octane of 87 or higher"
 

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My car runs well on 87. Your reference is a 2011 model. i don't own a 2011 Cruze. I will bow out on this thread. It is a free country and we all get to make our own choices. I will stick with what Chevrolet has in the owners manual. From my perspective if a 10% or more gain could be achieved from premium gasoline they would put 91 or higher in the owners manual and have car tested in an official way and instead of my 14 Eco 6 speed having 42 mpg it would be 42 mpg plus 10%. Comparing one tank of fuel to the next isn't a very scientific way of comparison. Driving conditions are different from tank to tank, traffic, temperature, whether you use a/c or not, whether it is winter blend gas or summer. I really don't buy into feelings or I think it is better. No hard feelings on my side.
 

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All owners manuals for every year say 87. The programming was changed in 14 to allow the cars to run better on regular, but they will still fall on their face at high ambient temps like the OP is experiencing. There is nothing physically different about the 14+ motors, and there is wrong with his car - it is normal for these motors in hot temperatures, sitting in traffic where the car will heat soak and pull timing.

Even our Toyota Camry knocks a bit in the summer on 87 octane. It's just physics. Manufacturers are pushing the envelope of the anti-knock properties of 87 octane fuel in normal temperatures, and then relying on the knock sensor to keep the engine from destroying itself in extreme summer temps.
 

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Discussion Starter #18
Maybe there is a problem with your car and should be taken to your dealer. I have never had 5 people in my car either. The back seat is only meant for small children in my view. I haven't tried higher octane but have been happy with the way my car drives and performs so why spend the extra $$$. Hope you get it figured out.
My 3 in the back are really more like 1 person weight wise ;)

3 kids, 6, 4, and 1. They probably weigh 100 lbs or less combined ;)
 

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Honestly just run 93 octane all the time, there's no reason not to. If you can't afford 30-40 cents more per gallon, then you shouldn't of bought a brand new car...no offense.
You mean someone who bought an economy car should expect to run premium octane? That comment doesn't make much sense to me, even though I run 93. The average person buying an economy car does not expect to use premium gas.

As to the OP's questions:
-Yes, Torque will allow you to watch timing and knock retard.
-The 14s and 15s supposedly have different ECU tuning that deals with 87 octane better, but you may still see advantages running higher octane. Why not run a tank of 91/93 octane and see if it makes any difference in your situation?
-Whether the MPG is good or not depends on your average speed over the course of the tank.
 

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You mean someone who bought an economy car should expect to run premium octane? That comment doesn't make much sense to me, even though I run 93. The average person buying an economy car does not expect to use premium gas.
I actually bought mine because I was tired of having to run 93 in my previous car.

I am fine running 91/93 in the summer, and the other months out of the year, my car gets fed 89. I figure that makes up for the increased cost with an improvement in drivability and MPG, but 93 is not worth it in the cooler months as there is less return (and 93 is 50-60 cents a gallon over 87 around these parts)
 
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