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Not getting the MPG I think I should

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So, my normal commute is 37 miles one way, with about a 2000 ft elevation gain on a 2 lane road. I've had worse commutes... That being said, I've been averaging about 33 MPG per tank. Ok, I understand with the mountain, that's not bad. But over the weekend, I took interstate from home to Black Mountain, NC. I-77 to I-40. Even with cruise control set most of the way at PSL (70, then 65) I only got 37 MPG average. On the way home, the trip started down a big mountain, so I was able to average 42. Not as good as I was expecting.
What items should I be looking at on my 2014 CTD?
I've already:
Changed all filters except the fuel filter. (Dealer changed that right before delivery, there is still 47% life on it.)
Put in amsoil oil and transmission fluid. (Flushed transmission)
Cleaned the MAF.
Tightened the 5 hose clamps from the air filter onwards.

I was thinking maybe have the dealer:
Reset the LTFT
Flash the HVAC (I have the humming noise when the car shuts off, and if I maintain 70 or greater with RPMs 2K or over, the A/C shuts down - but that's another story.)

Any other things I should consider?
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· COTM Winner
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You usually don't have to unless you over-oiled a K&N (or similar) air filter. I can't say I've ever cleaned an MAF in anything I've owned, ever.
 

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70.9 mph should be right at 2000k rpm, yes.
 

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Honestly, I think I've found this car likes doing 70 more than doing 60. Driving to NC the last time (going for the Hypercruzer badge), it really seemed to be happier (fuel-wise) at 70-75 mph than at 55 or 60 mph.
 
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I think the tires are original, I'll have to look. They have 5/32 left on them last I checked. Almost due for new ones, I am contemplating Continental Pure Contacts.
That probably won't help you on your quest for fuel economy. Certainly a better tire, but the OEM Fuel-Maxes are quite a bit lighter.
 

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Two tanks ago was 100% city (some stop and go), and it was 31.67.

Lifetime average is 38.6 with a pretty even split between city and highway.
 

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I wonder if your mods, especially the 19 inch tires had an impact of fuel economy? I would guess it could have. Made a trip yesterday from Indy area to Fort Wayne and got 52 mpg on way up and then economy dropped on way home to 47 with a strong cross wind. My car is bone stock other than tint. Interesting as well, my last regen was 89 miles, this tank I am at 350 miles and at 20 grams and been very slow since I got fuel. I wonder if my car has winter fuel or if lower temps outside give me more miles per regen? Dramatic difference.
Those look to be pretty lightweight wheels - so I wouldn't be surprised if they're actually lighter than the OEM 17's. That said, the tires are more than likely far heavier than the factory Fuel Maxes. What size tire and what kind of tire are they?
 

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Agreed. It's smooth, and if you were to re-engage cruise at a much lower speed, it doesn't immediately shoot to WOT in order to achieve said speed.
 

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Any chance the tires also changed the calibration of your speedometer and odometer? I am not familiar with what happens when you change tire size etc, maybe it changed your odometer to show less miles than actual miles traveled and that could make it look like your mileage sucks when maybe it doesn't? Just an idea.
If the tire diameter is not the same as the stocks 215/55R17s, then it will throw that all off - maybe a little, maybe a lot. Depends on the size of the new tires.
 

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crazy talk

yet to see a DIC pic of high mpg with high mph.
Our best tank ever of 57.4 was started just before we got back into Michigan (Ohio Turnpike) - as soon as we did, cruise was set up to 75 (and I went WOT to get there upon crossing the state line). We filled up about 100 miles later of a solid 75 mph on the highway (mixed with a couple miles of city), in ~40 degree temps, and got that.

Watching the instantaneous fuel economy - which was something I did the entire time I was driving down and back from NC - it really seemed to favor 70 mph vs 65 or 60 mph.
 
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