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Old 07-04-2010, 03:28 PM   #1
trashygasman
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Default bad fuel mileage!

I have a 09 LTZ with L4 and 6 speed. It has 16k miles on it. 27mpg is the best it has ever gotten. I have driven fast and driven it slow. I drive 50 miles one way to work every day. All 4-lane or interstate. Just wondering if anyone else is getting bad mileage and what you have done to fix it. The dealership told me they haven't heard of any mileage problems, but they will reflash the ECM and see if that will fix it.

Last edited by trashygasman; 07-04-2010 at 03:58 PM.
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Old 07-04-2010, 05:50 PM   #2
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Default Re: bad fuel mileage!

There are a lot of variables that account for your MPG, what kind of highway/interstate is it you drive in? Hills, mostly flat, or steep mountain type roads?

I tried to see how high I could get my MPG on a road trip from LV to OR, 33 was the highest I got it. That was driving at the speed limit and drafting behind other vehicles helped out too. I made sure to have my tires properly inflated and had just changed the oil too.

That was the first and last time I'll do that, your 27 seems to be a more realistic number though.
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Old 07-04-2010, 06:41 PM   #3
Richard
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Default Re: bad fuel mileage!

Quote:
Originally Posted by trashygasman View Post
I have a 09 LTZ with L4 and 6 speed. It has 16k miles on it. 27mpg is the best it has ever gotten. I have driven fast and driven it slow. I drive 50 miles one way to work every day. All 4-lane or interstate. Just wondering if anyone else is getting bad mileage and what you have done to fix it. The dealership told me they haven't heard of any mileage problems, but they will reflash the ECM and see if that will fix it.
Try resetting the average MPG just as you are getting on the highway. The trip computer will keep an ongoing average from your prior driving, so make sure you reset it just as you get on the highway. See what you are averaging after your highway driving. You should be getting in the 33 mpg range. I generally do even better than that, somewhere around 33.7. If you are getting 27 MPG doing only highway driving, then something is wrong. However, with mixed highway and city (stop and go) driving, 27 MPG would be okay.

The only area I thought I would do better is straight city (stop and go) driving. Where I live, you can hit a traffic light on every corner. I expected to get around 16 MPG doing only this type of driving. I've been averaging 14 MPG. I know it's a heavy car and I have been using the A/C, but with a 4 cylinder, I thought I would do better than that.

Last edited by Richard; 07-04-2010 at 06:43 PM.
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Old 07-04-2010, 09:10 PM   #4
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Default Re: bad fuel mileage!

I'm down from 34-35 to 31 in mixed (2/3 of my driving on interstate and beltway, average speed @ ~40 miles/hour combined). I suppose A/C takes a toll. My MPGs are actual (as opposed to the DIC) from miles driven vs. gallons used. I drive alone, with not much cargo, ~10 lbs of emergency stuff in the trunk. I suppose 27 isn't far-fetched given the heavier LTZ.
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Old 07-05-2010, 08:16 AM   #5
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Default Re: bad fuel mileage!

When I've used the method that Richard suggests, that of resetting the DIC's Avg MPG just as I get onto the freeway, I've actually been able to get it up to 36.1, and I've got the V6!

A couple of months ago I was returning with my sister from Elizabethtown to Louisville on I-65 North. The speed limit is 70 for most of it but I was doing 60. We had gone 70 on the southward leg but wanted to see how much that extra 10 mph did to the mileage. There aren't any mountains on that part of the road but there are a lot of rolling hills and a few steep passes, but no large elevation changes (probably 100-400 feet each). Most of the way it was registering around 34-35. When I got closer to town and the limit dropped to 55 it started to go up again. Once I got off the freeway and hit surface streets it started to plummet, but that's to be expected.

I used cruise control all the way, tapping off only when traffic required it. And the AC was on.
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Lost: '11 LTZ RJT V6 / A6 in flood at 44K miles
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Old 07-05-2010, 10:07 AM   #6
trashygasman
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Default Re: bad fuel mileage!

I just thought it would have gotten better. We had an 03 Accord before this, and it averaged 30-32 with the same driving. I think the 6 speed hurts it more than anything. Any type of incline and it has to downshift all the way to 4th to catch up.
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Old 07-05-2010, 06:34 PM   #7
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Lightbulb Re: bad fuel mileage!

Quote:
Originally Posted by trashygasman View Post
I just thought it would have gotten better. We had an 03 Accord before this, and it averaged 30-32 with the same driving. I think the 6 speed hurts it more than anything. Any type of incline and it has to downshift all the way to 4th to catch up.
I'll agree in principle that the A6 is not a performer. I can force it into a gear more easily by using the tap shifters than I can by using the ol' press-and-release of the skinny pedal.

Mine doesn't go to 4th when it downshifts to regain lost speed up a hill. One way I know that is after it shifts, sometimes I'll pull it into "M" and it says 5th. I was curious because it sounds like it's up-shifting twice once it gets back to the preset speed. I'm sure others who feel like commenting will assure you that first it shifts up from 5th to 6th gear and then it locks the torque convertor. TCC lock is what feels like the second shifting of a gear, making you (and me at the time) think it had down-shifted to 4th and then had to up-shift twice to get back to 6th.

See if your air filter is excessively dirty, ensure that you're using the correct grade of gas (for V6 GM recommends 87 or 89), and that your fuel system is not compromised by dirt or deposits. Most of the time I use top-tier gasolines, and occassionally I fill with mom-and-pop gas, but that's rare. I always use 89. I no longer waste my money on 92 and don't want the reduced performance of 87.

Another thing to consider is that I took off my huge muffler that is overly restrictive and put in its place a Y-pipe and dual resonators, along with the original factory dual tips. Sounds better, but regarding this thread, it might also be giving me an improved exhaust flow through lower restriction, enabling the slightly higher MPG numbers. Or not. But it isn't hindering it any, of that I'm sure.
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V6/A6, Red Jewel Tintcoat / Cocoa-Cashmere, Sunroof
Mods: WeatherTech mats, CHMSL Pulser

How-to: LEDs in mirrors :: How-to: 1-Wipe Wash
How-to: Remote express windows up/down


Traded: '09 2LT Black Granite Metallic V6 / A6 at 20,058 miles
Lost: '11 LTZ RJT V6 / A6 in flood at 44K miles
Muffler mod on '09

Last edited by DrivenDaily; 07-05-2010 at 06:37 PM.
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Old 07-06-2010, 11:53 AM   #8
RaineMan
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Default Re: bad fuel mileage!

I hate to say it... but have you considered slowing down?

My commute is 99% highway and I'm averaging 25MPG with the 3.6. That's running 75-80 the whole time and kicking down to pass at will. My mileage goes up to 27 or 28 if I just stay in one lane and do 65-70.

Just cruising on the highway you should be able to get 30MPG no problem out of that 2.4.

The 6-speed is wonderful in these cars. Not only does it enable the 3.6 to really scoot, but it keeps the 2.4 in the heart of the power band, making the most of the available170hp.

You also have to consider that this car weighs more than your Accord. The 2003 Accord tips the scales at ~3300lbs. The 2009 Malibu LTZ is ~3600... 300lbs difference. That's like carrying around a football player.

What octane are you running? I know the manual says it will do fine with 87, but the 2.4 prefers premium. I go by the old muscle-car saying, if compression is over 10.0:1, use premium.

Finally... how hard are you accelerating? To get the most out of the 2.4 you have to keep the revs pretty high, above 4000 where the cam timing kicks over, if you are running the engine at above 4000RPM a lot then your mileage will also suffer. One of the reasons I went for the V6. I can get performance out of it adequate to keep up with traffic without going above 3000RPM.

Last edited by RaineMan; 07-06-2010 at 12:01 PM.
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Old 10-25-2012, 04:32 PM   #9
ecclampitt
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Default Re: bad fuel mileage!

My 2011 Malibu has only gotten 19 mpg average. I am so frustrated with the car that I am beginning to hate it! I asked the dealer about it and they said they couldn't do anything about it! It doesn't matter whether I go local or highway, fast or slow! Does anybody know what I can do? Thanks.
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Old 10-26-2012, 03:30 AM   #10
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Default Re: bad fuel mileage!

Average over how many miles? I have an '11 V6 and my lifetime average across 29,000 miles is 19.707. I usually get around 18-20 in town and can get 25-30 on highway.

How are you determining your mileage - by the DIC or after filling up and doing the math? The DIC should be fairly accurate, but if you never reset it you'll get lifetime average (possibly covering only 1000-2000 miles, not sure). Resetting it after each tank will yield tank averages.
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'11 LTZ, born Aug 2010, Fairfax, KS

V6/A6, Red Jewel Tintcoat / Cocoa-Cashmere, Sunroof
Mods: WeatherTech mats, CHMSL Pulser

How-to: LEDs in mirrors :: How-to: 1-Wipe Wash
How-to: Remote express windows up/down


Traded: '09 2LT Black Granite Metallic V6 / A6 at 20,058 miles
Lost: '11 LTZ RJT V6 / A6 in flood at 44K miles
Muffler mod on '09
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