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Discussion Starter #1
I'm into my 3rd week of owning my 3.6 2005 CTS and am really disappointed in the fuel economy in comparison to the Aurora I used to own. The CTS is a lighter car with basically the same size engine and I can't seem to get over 23 MPG on the highway whereas I was getting 27+ in the Aurora. If I set the DIC to instant MPG, it never really goes above 24/25 MPG on the highway @ 65-70 MPH. Is this typical? If it's not, what can I check to see if everything is working properly? The air filter is new, and I don't have any lights on. I see this car has a ridiculous amount of 02 sensors. (5 of them?!)
 

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04 CTS SPORT/LUX W/NAVI LIGHT PLATINUM ON BLACK- COOL MODS!
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The Fuel economy for this car sucks, especially if you live in the city. Once again, my numbers:

11-13 City
21-24 Highway

And no, nothings wrong with the car. Thats just the way it is...........

:(
 

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Check out my CTS here: http://www.fquick.com/FL01SS
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Mine's been averaging 17 city & 24 highway. That's only if I baby it.
 

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Even with my 3.2 my mpg on the dash is quite a bit higher than everyone elses. I mean I was driving in the city today and I reset my average and was getting 23-24 without the a/c on.

ha I'm going to check to make sure the odometer is working right.
 

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2008 CTS Radiant Bronze, Performance Collection RWD
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I have had my 2004 CTS since new. I regularly get 21-22 mpg city and 25-27 on the highway and it has 75000 miles on it.
 

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'04 CTS
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In mixed suburban driving where I use the interestate to jump between areas I get about 21 mpg. On a recent trip (1100 mostly interstate miles) I got ~27. On the same trip last year, my Olds Intrigue 3.5 got ~28.5 and an older Intrigue with the 3.8 used to get ~29.5. All these numbers were during summer months with the A/C running. The odometer is right on the money but the mpg indicated on the dash is optimistic by about .7 mpg. If I use "Sport" mode then mpg really goes to hell.
 

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91 Allante (gone), 06 SRX (gone)
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It seems low to me. My 04 CTS 3.6 averaged about 24.5 MPG on the DIC and on the highway, instant MPG often read 28-30. My driving was 80% highway (I-96) with an average speed, per the DIC, of about 45. My mods were a Volant intake and CTS-V catback exhaust.

BTW, my stock SRX (RWD, 3.6) averages about 21.5 MPG on the DIC.
 

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On a recent 300 mile run with my 06 3.6 I averaged 27.4 with the AC on. I noticed the mileage usually increases from 75 to 80 mph over 65 to 70. I'm not saying that to be funny either...LOL The best number I ever got was 29 on a run to Baltimore which is about a 5 hour ride for me. I attribute that to making only one stop and driving most of the run at 75. I run 89 oct in my car also.
 

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I agree on the 89.. I could tell a performance hit with the 87 and no difference between 91 and 89.

Btw my mileage was about 4 mpg lower than it is now on a mix of highway and city when I first got my car but I realized the dealer only had about 31 psi in my michelins and they take 44psi. Helped out slightly. :)
 

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2005 CTS 3.6L, 2006 350Z, Ducati 996s
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My guess is that your Aurora had the 4 spd, 4L60E I think, with the talll final gear. In which case, you would get better mileage in the Olds. A CTS will pull even the 4.0L Aurora after about 30 or 40 mph, thats one of the benefits.

23 mpg on the highway at 65-70 still is pretty low tho.
 

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CTS
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Discussion Starter #13
The Aurora had the 3.5L V6 with the 4t65E transaxle with 3.27 final gear ratio. :) The CTS is definitely a LOT faster. ;) I'll check the tire pressure. I didn't even think of that.. :thepan:
 

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2014 ATS Performance 2013 SRX Premium
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First off milage tested over 2000 miles of driving, 23.2 mpg, averaged during 70% highway driving 65-80 mph. Recently 367 miles on a tank - maybe 1 gallon left in reserve. Spent the last week doing around town driving 90+ temps average 20.4 mpg. DIC indicates 27-28 instant mpg at 70-75 mph

Tire pressures. If I set cold pressures to 31 psig and drive 30 highway miles to work the tires heat up and my pressure increases to 35 psig. If you set tires to 44 psig like Kuhlsnu you may be asking for trouble
 

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2007 CTS White Diamond - 1997 Deville Silver Mist
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I'm into my 3rd week of owning my 3.6 2005 CTS and am really disappointed in the fuel economy in comparison to the Aurora I used to own. The CTS is a lighter car with basically the same size engine and I can't seem to get over 23 MPG on the highway whereas I was getting 27+ in the Aurora. If I set the DIC to instant MPG, it never really goes above 24/25 MPG on the highway @ 65-70 MPH. Is this typical? If it's not, what can I check to see if everything is working properly? The air filter is new, and I don't have any lights on. I see this car has a ridiculous amount of 02 sensors. (5 of them?!)
I had the same concerns as well. I have a new '07 with the 3.6 and the best I've got on the highway so far is 24.8 MPG. It had gone as high as 25 MPG, but dropped slightly as I continued to drive. I had 2 Caddy's with the Northstar V8 engine that got better mileage than that. And my brother has a 2004 Maxima which has a very similar engine to the CTS and he gets over 28 MPG on the highway.

I was pretty surprised how poor the MPG is on the CTS. I think it's mainly due to the weight of the car. The CTS is a pretty heavy car for its size.

So I wouldn't be concerned that anything is wrong with your car. It just doesn't get very good gas mileage.
 

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Discussion Starter #18
I put my tires up to 39 PSI. Hopefully that'll help in the gas mileage department. It surely does ride a bit rougher though. The tires from the dealer were only at 29 PSI!!
 

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I've got an 06 with 9,000 miles, air pressure 33 psi. Three weeks ago I tanked up, reset the computer, drove thru town, got on the interstate, drove 61 miles at 60-65 mph (10 under prevailing speeds), and the computer was showing 30.7 mpg at destination. Last January I was driving across Oklahoma, had a strong tail wind, so I decided to see what the car was really capable of. I filled up, reset the computer, drove 40 miles at 55 mph. The computer was showing 33.1 mpg at the end (no A/C). Of course, that was a REALLY good tailwind! It got 28.7 at 70 mph across AR/TN/VA, lights on but no A/C. Oh yeah, I always get 19-21 around town, but it drops 2-3 mpg with A/C, in town or hiway. I expect it to drop soon when the "winter gas" comes out.
 
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