# bad MPG? What is the culprit?



## Mo Cruze (Aug 29, 2014)

Seems everyone on here gets better gas mileage than me. I dont get it. I dont drive like a mad man or anything. Is there anything that could be causeing my cruze to have poor MPG? My intake is clean.. Anything else that can affect gas mileage? the highest ie ver got was 28.1 on the dash. Trying really hard. Now im averaging 26.9 in the last almost 3000 miles. And that really only like 25 b/c my dash projects about 2 mpg over actuall.


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## NickD (Dec 10, 2011)

Winter gas is not the problem in Florida, use to seeing my miles remaining well over 640 mile after a fillup. If I can hold it under 65 mph on a long trip, getting well over 44 mpg using the long division method, distance divided by number of gallons consumed.

Only modification to my Cruze 1/4L was getting rid of those stupid NGK plugs and switching to Autolite's APP 3923's gapped at 26 mils. And stretching those boot springs out so they don't hand up in the boots. Only use top tier 91 octane ethanol free gas, in my neck of the woods, Mobile is the best.

Last tank dropped to 33.9 mpg, have to live with winter gas, but expecting this tank to drop to 30 mpg and have been this way for the last three years. Over the last summer, has been in the 39.7 mpg range with combined city and highway driving. I do not fly up to a traffic or stop sign to slam on the brakes like most drivers do, then nail the gas pedal to the floor when taking off again.

Usually drive at 72 mph on the interstate, any slower would get ran over.


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## Merc6 (Jun 8, 2013)

What PSI is your tires and what brand/grade of gas are you running? How is the weather down there? Are you sitting in traffic with a/c on?


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## brian v (Dec 25, 2011)

Hay don't tell OP , But did'nt Danny get rid of his cruzen because he Hydrolocked IT .. 

Maybe OP got Danny"s old cruzen ..would'nt that be a hoot .


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## spacedout (Dec 7, 2010)

Too little to go on.... When you reset your trip computer at fill up, what is your average speed for each tank? Really need to figure out how much city driving your doing. Stop and go traffic & idling is the main culprit to poor mileage.


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## Merc6 (Jun 8, 2013)

spacedout said:


> Too little to go on.... When you reset your trip computer at fill up, what is your average speed for each tank? Really need to figure out how much city driving your doing. Stop and go traffic & idling is the main culprit to poor mileage.


yeah , stop and GO GO GO. Also I been trapped behind this car forever and floor it well after you passed them to make up for the time you lost behind slow poke.


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## grs1961 (Oct 23, 2012)

Have you gapped your spark-plugs correctly?


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## NickD (Dec 10, 2011)

You mean like when Nixon dropped the interstate speed limit to 55 mph, to save on fuel usage. When 90% of the people in cities were trying to dive in stalled traffic?

Truckers really complained, were geared to get the best fuel economy at 70 mph. Not only many extra hours on the road, but poorer mileage as well. Was driving my 70 Buick Rivera back then, was getting 20 mpg at 70, dropped to 17 at 55.

So what kills? Is it speed or pure boredom?


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## tracepk (Aug 20, 2013)

I recently moved from 20 miles out of town to right on the edge of town, my avg mpg per tank dropped from 38mpg to 26mpg now that im doing almost all city driving :/


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## NickD (Dec 10, 2011)

This is what my Window sticker has to say on this subject?

City MPG 26
21 to 31 mpg for most drivers.

Highway MPG 38
31 to 45 mpg for most drivers.

Looks like you are in the city expected range.


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## Mo Cruze (Aug 29, 2014)

spacedout said:


> Too little to go on.... When you reset your trip computer at fill up, what is your average speed for each tank? Really need to figure out how much city driving your doing. Stop and go traffic & idling is the main culprit to poor mileage.


I think my average speed is like 27 ill have to check when i get in my car again. I do probably 70% highway. Speed limit 70. South Florida.


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## Mo Cruze (Aug 29, 2014)

Merc6 said:


> What PSI is your tires and what brand/grade of gas are you running? How is the weather down there? Are you sitting in traffic with a/c on?


Of course i have my AC on always lmao! Im in south florida. Its always hot. Thats the weather. Runnin regular gas. Ive seen so many people say mileage doesnt change with gas grade. psi i have at 32. 17inch LT2


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## Mo Cruze (Aug 29, 2014)

grs1961 said:


> Have you gapped your spark-plugs correctly?


No i havent had a chance to touch them yet. And to be honest im a bit nervous after hearing everyone ripping their boots! could this affect gas mileage?


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## Mo Cruze (Aug 29, 2014)

NickD said:


> This is what my Window sticker has to say on this subject?
> 
> City MPG 26
> 21 to 31 mpg for most drivers.
> ...


Well thats how i feel like im in the city expected range when i do mostly highway. I feel like i should be gettin at least 30 MPG with the amount of highway driving i do. I just feel i should be getting better gas mileage. If i see a light red i glide to stoplights not hold the gas and then slam on the brake like NICK D mentioned. Constantly monitoring the "realtime" MPG on the odometer trying to hit as high as possible. Yes if i pull out in front of someone i punch it or if i need to make it through a light when its orange. lol but for the most part i drive it like my grandma. Maybe it is what it is. We need to do a poll and see what everyone on the site MPG is.


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## Merc6 (Jun 8, 2013)

Mo Cruze said:


> No i havent had a chance to touch them yet. And to be honest im a bit nervous after hearing everyone ripping their boots! could this affect gas mileage?


Heat and 87 octane could play a factor as well as A/C(is it on the far left where the blue line becomes a dot?) usage at those speeds. Yeah I was down there last year on Tyndall for training and small amount of R&R. I managed to get 3 shades darker in like 2 weeks.


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## Mo Cruze (Aug 29, 2014)

Far left where blue line becomes a dot? huh? You lost me there?


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## Merc6 (Jun 8, 2013)

Mo Cruze said:


> Far left where blue line becomes a dot? huh? You lost me there?


This part of the knob


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## Mo Cruze (Aug 29, 2014)

yes lol its all the way cold....?


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## Robby (Mar 1, 2013)

A few things I think you should do to help determine the real attainable mileage.

Set your cold tire pressure at the pressure posted on the door opening decal....I think yours is 35 psi.
Or, if you want to see the best it can get by controlling rolling resistance, air up to maximum sidewall pressure posted (44psi).

Having been in Florida, I know you don't have to run the A/C every day to survive and there are no mileage ratings for A/C on.
A/C compressors pull between eight and fifteen HP and that is variable depending on ambient temperature....this must be done with A/C off.

Go somewhere that will allow about thirty minutes at 60 mph.....The idea here is to keep RPM at 2000 or slightly below.
Set the cruise at the speed/rpm above and once settled in, reset the trip one average......resist the urge to change road speed.

The average displayed, after thirty minutes, is a fairly close representation of what your car can achieve under almost perfect conditions.....not unlike the conditions created for the EPA numbers.
Now, turn it around and turn on the air and drive in your usual fashion.

If you are like 99.9% of drivers your average will go down....far more than you expect.
The difference between the two represents how your habits and usage affect the potental the car can achieve.

Keep in mind, this average is displayed is close to actual but likely a a varience of five percent can be expected betwwen the readout and reality......close enouph though for this question.

Rob


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## jblackburn (Apr 14, 2012)

EPA ratings do include AC usage into the cycles. 

However...the tests are also done on 91 octane no ethanol gas to keep results consistent between vehicles. 

AC usage, hot weather, heavy city driving, and especially 87 octane usage are killing your mileage (87 oct and load from the AC compressor absolutely neuters the car at low RPM, resulting in lots of pulled timing and wasted fuel). 

Gas is cheap now - try a tank of 89 or 93 and see what happens.


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## obermd (Mar 3, 2012)

Mo Cruze said:


> Of course i have my AC on always lmao! Im in south florida. Its always hot. Thats the weather. Runnin regular gas. Ive seen so many people say mileage doesnt change with gas grade. psi i have at 32. 17inch LT2


Run your car on 89 or 91/93 octane. 87 simply doesn't do the job when it comes to fuel economy for most of us. CEBT (in Idaho) is about the only member here who almost never loads his engine so running 87 is perfect for him. For the rest of us heat and driving under load (engine, not the driver) will heat soak the intercooler and turbo-charger, leading to even more knock and reduced drivability as the ECU pulls ignition timing to protect the engine. As for increased fuel economy, take a look at 2011 Chevrolet Cruze Long Term Road Test - MPG for a non-forum review of the Cruze running on regular vs. premium gas. Of course the amount of benefit you gain from premium is offset some by the extra cost of the fuel, which is why I have repeatedly recommended people give mid-grade (89) a try as well. For many drivers the performance gains from mid-grade outweigh the extra cost but premium is too expensive. My ECO MT is simply a jerky slug when I use 87 octane in the summer heat with the throttle pulsing like crazy during the non-existent acceleration. On 91 it smooths out and I don't lose significant power with the A/C running. Based on my testing, even the LS with its 1.8L non-turbo engine benefits from 91 octane.



Mo Cruze said:


> No i havent had a chance to touch them yet. And to be honest im a bit nervous after hearing everyone ripping their boots! could this affect gas mileage?


The incidence of boot ripping are relatively rare, but inconsistently gapped plugs in this car are a huge issue and can and do affect drivability and fuel economy. Even the 2014 owner's manual implies the plugs aren't guaranteed to be gapped consistently from the factory. In addition, those of us who have been monitoring our plug gap have seen inconsistent gap growth with cylinder 4 (right side from the driver's seat) growing the fastest.

Edit: Boost your tires to at least 35 PSI. If you can handle the higher pressure go all the way up to max sidewall. I find the car handles far more predictably at max sidewall pressure and it does reduce rolling resistance and increases tread life.


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## just a cruzer (Nov 23, 2014)

If your car is a stick, try down shifting more often. giving it a little more rpm helps keep it from bogging down. Mine seems to do better anyway. 
I always thought the higher rpm would use more fuel but in actuality bogging it down just makes it work harder and I always had my foot in it. 
also, I never put cheep fuel in mine.. spend the few extra cents, you get more bang for your buck and your car will love you for it.


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## Merc6 (Jun 8, 2013)

just a cruzer said:


> If your car is a stick, try down shifting more often. giving it a little more rpm helps keep it from bogging down. Mine seems to do better anyway.
> I always thought the higher rpm would use more fuel but in actuality bogging it down just makes it work harder and I always had my foot in it.
> also, I never put cheep fuel in mine.. spend the few extra cents, you get more bang for your buck and your car will love you for it.


Believe he is an auto so M Mode can be used to do similar. 

Welcome to the forums.


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