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Discussion Starter #1
I noticed tonight that my display says I am getting 31MPG. I have never gotten more than 21MPG.

I recently filled all of my tires as they were all between 25-28psi. They are all at factory 30psi now.

I have a Volant intake also.

I think this is one of the below:

a. the damn computer is on the fritz
b. adding the air to the tires boosted the mpg
c. I am in Northern VA and it has been 25-35 degrees for the last few weeks and the Volant is really getting cold air now.
d. combination of b and c

What do you guys think?
 

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2003 CTS
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In my experience, I would guess D. It's probably a combination of things. Increased air pressure in your tires will definitely increase your mileage as will the cooler charge from the intake. Another thing to consider is...have you done more freeway driving as of late and not so much "around town" driving. I think it's highly unlikely that your ECU is on the blink already. Manufacters usually have the electronics pretty well dialed in. Unless...your car happened to originate in the S. Florida or New Orleans areas. Then that ECU could do pretty much anything at anytime. Hope that helped some.
 

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MPG on the DIC isn't really accurate to begin with. Its interpolated from various onboard data. Its possible that you are getting 31 MPG. You didn't say whether that was the avg MPG or just the MPG on the display as you drive around. I can get my MPG to go to 70 MPG while I coast to a stop at a red light, so its all relative.
 

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Discussion Starter #5
jteolis said:
You didn't say whether that was the avg MPG or just the MPG on the display as you drive around.
No it is the average, not the instant mpg. That is why I reset it last night and drove about another 50 miles and it went back up to 31 MPG. I was highway driving about 60-70, I have the 3.6L. I have to refill the tank this morning and I will reset the gallons used and the MPG average to see if it gives me the same readings. I will also set the trip meter and do the math the next time I refill to back up what the DIC is telling me.
 

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Discussion Starter #7
I just filled up and reset everything except the oil life on DIC. Drove it on the highway for an hour at 65-70 and I have 23 mpg. I checked that against my odometer and it checks out.
 

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I'm voting computer glitch too. Colder air doesn't give you better mileage, and 3 more pounds of air in the tires is almost immeasurable. My 3.6 gets about 26 mpg on the highway at 115kph or so. Kinda disappointing in that my LS1 Z28 got a few mpg better than that.
 

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Ilyesha said:
I just filled up and reset everything except the oil life on DIC. Drove it on the highway for an hour at 65-70 and I have 23 mpg. I checked that against my odometer and it checks out.
That's more like it. I get about 23-26 mpg on the highway and about 20mpg city driving. The only problem on my is when I fill-up, the gas pump says 15 something gallons and my DIC fuel used only shows about 14 gals. DIC always shows at least 1 1/2 gal. less. Not sure if the gas pumps are off or my DIC is off.
 

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this is a pretty funny story. I'm going to Texas for a very sad funeral, anyway, I'll be driving people around and the largest rental car they have is an 04 Deville, so I say OK.

Anyway, I'm playing with the DIC and see the average MPG, and that v8 northstar starts getting better and better MPG. The FASTER I drive, the better it gets!

I say to my wife WTF! This fricken Deville does better than my V6 CTS back home -- 35 MPG? I'm MARVELING at the apparent MPG this car is getting! Then my wife points out to me that its says "Average MPH" NOT MPG!

Priceless!!
 

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jteolis said:
I say to my wife WTF! This fricken Deville does better than my V6 CTS back home -- 35 MPG? I'm MARVELING at the apparent MPG this car is getting! Then my wife points out to me that its says "Average MPH" NOT MPG!

Priceless!!
roflmao.:histeric: :histeric: :histeric:
 

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Discussion Starter #12
jteolis said:
I'll be driving people around and the largest rental car they have is an 04 Deville, so I say OK.
Yep, I had a Deville as a loaner when my CTS was getting serviced. I remember I needed to 6 poiont turns to park as the turning radius was insane. And once i was parked I didnt put it in park, I just opened the trunk and dropped anchor!!:histeric:
 

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Ilyesha said:
I noticed tonight that my display says I am getting 31MPG. I have never gotten more than 21MPG.

I recently filled all of my tires as they were all between 25-28psi. They are all at factory 30psi now.

I have a Volant intake also.

I think this is one of the below:

a. the damn computer is on the fritz
b. adding the air to the tires boosted the mpg
c. I am in Northern VA and it has been 25-35 degrees for the last few weeks and the Volant is really getting cold air now.
d. combination of b and c

What do you guys think?
Appalachia must be some sort of freak area where our DIC's go on the fritz. Right after I bought mine I took a road trip to west virginia and averaged nearly 30 mpg all the way there and back. I've never seen anything near those numbers since. (I average between 20 and 25 MPG now)

I dont know about northern VA but down in West VA a CTS must be a rare vehicle because I cant tell you how many times I got asked, "what the heck is that?" b/c no one had seen one before.
 

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Discussion Starter #14
DDS rollin a CTS said:
I dont know about northern VA but down in West VA a CTS must be a rare vehicle because I cant tell you how many times I got asked, "what the heck is that?" b/c no one had seen one before.
Well, if it ain't a pick up in WV they won't know what it is. After all the state flower is a satellite dish!
 

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It'possible with highway driving. This past fall I made a trip to Vegas and got 31 mpg from Ogden UT. to Boise ID. The trip average was 28.5 overall for the 2000 mile round trip.
 

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Have a 2005 Platinum 3.6 with 6000 miles on it. Be very please with the cars gas mileage. On the Hwy @70 I average about 30-31MPG...however @80 it drops back to 27MPG.
 

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i got the 3.2 and i more often than not get 30+ mpg on my 120 mile trip back home. I always take back roads and drive at least 85 pretty much the whole way. It is pretty much perfect conditions though. Never that much wind, almost completely flat roads. Its awesome. Also, how many people here use at least 92 octane?
 

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My average speed on the trip I mentioned above was probably around 80mph or so. I'm going up to Minnesota to visit family for the new year (anyone in the Minneapolis/St Paul area feel free to chime in with good places to go when the family gets to be too much!!!) and I'll be sure to monitor my mileage for that trip as well.
 
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