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2009 CTS4 Premium & 2012 SRX4 Luxury
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Discussion Starter #1
First two tanks of 87 octane I ran since buying the car in Jan I averaged 18.4 mpg. Judging by other threads I've searched such as http://www.cadillacforums.com/forums/2008-2013-cadillac-cts-general-discussion/281561-gas-mileage-2009-cts-all-wheel.html this seems to be typical for my commute and car. Coming from a 3.4L V6 that averaged 25 mpg on the same commute, this is disappointing, so I'm looking for ways to improve this.

What I found interesting is that I got 19.2 mpg running 89 octane, and just registered 20.6 mpg using 93 octane. These numbers are calculated based on miles driven and gallons used, not estimated figures from the DIC. Obviously there's still some margin of error but the driver and route was the same for all miles driven, and fuel was purchased from the same station.

Has anyone else noticed a difference in mpg using different octane fuel? With the DI engine I wouldn't think this should make much difference but then I've also read some info that KR is common with 87 in these engines.

I just refilled with another tank of 87 and this time I'm going to drive using the "Sport" trans mode to see what difference that makes. I'll follow that up with another tank of 89 and 93. I'm also planning to swap out the plugs in a few weeks after it warms up some. 68k miles on the car now and I'm guessing they're probably original.
 

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2001 SLS & 2012 CTS
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57 Posts
I've been driving my '12 CTS4 on mostly 2 lane roads on my commute to work (32mi each way).
Lately is has varied based on how cold it is outside, but it has ranged from 18.8 to 20.5.
Seems to be at 20 unless I'm on bad snow covered roads or the temp is in the teens or lower.
I do remote start it & let it run for approx. 3 minutes twice a day, so this also hurts the mileage.

Never tried different octane other than 87.
 

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2011 CTS Coupe
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263 Posts
I am averaging ~16 mpg in my rear wheel drive 3.6. My 3.0L turbocharged BMW averaged 21 mpg combined and could actually hit 29 mpg on the highway cruising at 70.

I am a little disappointed at the gas mileage in the caddy, but I didn't buy it as an econobox, so I will live with it.

Shakey
 

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2014 CTS Vsport Premium
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121 Posts
I have a 2011 3.6 awd sedan with 24k miles, I average about 18.9mpg in summer and 16.5 in the winter. Remote starting your car is a mpg average killer. I've seen it drop to 13mpg just from remote starting it 2 times a day for a month. They should write a better algorithm to sense when the car is remote started and idling. It also reads 0 mpg when you are sitting at red-lights, that kills it too.
 

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2011 CTS AWD Sedan performance
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27 Posts
2011 AWD sedan, 36k KMS, highway 28.5 and 22.6 miles per imperial gal. Very happy with car, came from a Jetta that got 46 miles per gal, but very boring car. The CTS puts a smiles on my face every time I drive.

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BRP1616 said:
2011 AWD sedan, 36k KMS, highway 28.5 and 22.6 miles per imperial gal. Very happy with car, came from a Jetta that got 46 miles per gal, but very boring car. The CTS puts a smiles on my face every time I drive.
22.6 city
 

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08 CTS blk/blk
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383 Posts
Ive owned my 08 AWD for about 4 years and I get about 19-20 mpg. I took it out to Ohio once and got about 23 on the highway. This is a heavy vehicle and dragging the AWD around does not help. Previously I owned an 05 CTS and that got 30 mpg on the highway. I can only recommend keeping it tuned up and keep your foot out of it. Best of luck
 

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2001 SLS & 2012 CTS
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Funny thing is that I get almost the same mileage that my 01 Cadillac SLS w 4.6 V8 did on the same commute.
At least I don't get stuck in the snow now... lol
 

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2011 CTS Coupe AWD Performance
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I have a 2011 Coupe with 3.6DI AWD. I run 87 octane because that's what the owner's manual recommends. Based on what the trip computer tells me, I have never averaged more than 24 MPG on the highway. Combined I average around 17 MPG. This is such a joke for a V6, far below the EPA estimates.
 

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Cadillac Owners Troll
2019 CT6 Sport 3.0TT,2015 Luxury ATS , 2016 ELR, and Volt
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First two tanks of 87 octane I ran since buying the car in Jan I averaged 18.4 mpg. Judging by other threads I've searched such as http://www.cadillacforums.com/forums/2008-2013-cadillac-cts-general-discussion/281561-gas-mileage-2009-cts-all-wheel.html this seems to be typical for my commute and car. Coming from a 3.4L V6 that averaged 25 mpg on the same commute, this is disappointing, so I'm looking for ways to improve this.

What I found interesting is that I got 19.2 mpg running 89 octane, and just registered 20.6 mpg using 93 octane. These numbers are calculated based on miles driven and gallons used, not estimated figures from the DIC. Obviously there's still some margin of error but the driver and route was the same for all miles driven, and fuel was purchased from the same station.

Has anyone else noticed a difference in mpg using different octane fuel? With the DI engine I wouldn't think this should make much difference but then I've also read some info that KR is common with 87 in these engines.

I just refilled with another tank of 87 and this time I'm going to drive using the "Sport" trans mode to see what difference that makes. I'll follow that up with another tank of 89 and 93. I'm also planning to swap out the plugs in a few weeks after it warms up some. 68k miles on the car now and I'm guessing they're probably original.
I average 20mpg in suburban driving on a rwd car so you are in the ballpark. These engines have knock sensors and have some upward leeway on timing if you run premium or midgrade so it's normal to get somewhat better mileage. You have to do the math to see if it is worth it.
 

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2009 CTS4 Premium & 2012 SRX4 Luxury
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Discussion Starter #10
Well I just ran a tank of 87 on "Sport" mode and got 20.7mpg, the highest yet. Filled up with a tank of 89 tonight so we'll see if that increase continues. When the price difference between the grades is only 10 cents or so it makes sense to buy the higher octane if it yields 1-2mpg better.
 
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