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Discussion Starter #1
I have a 12 Charger with the 3.6 and 5 speed. I live in a small town with not much stop and go traffic. I get 20 to 21 MPG in town. When I go to Louisville which is about 50 miles I get about 23 MPG. 70 MPH my RPM is about 2000.
The only mods I have done is mid muffler delete. Why the crappy interstate MPG?
My GF has the same car 1 year newer with the 8 speed her city MPG is a little better. Her interstate MPG is about 30 driving the same speed and road.
 

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I have a 12 Charger with the 3.6 and 5 speed. I live in a small town with not much stop and go traffic. I get 20 to 21 MPG in town. When I go to Louisville which is about 50 miles I get about 23 MPG. 70 MPH my RPM is about 2000.
The only mods I have done is mid muffler delete. Why the crappy interstate MPG?
My GF has the same car 1 year newer with the 8 speed her city MPG is a little better. Her interstate MPG is about 30 driving the same speed and road.
The highway gearing you have in the NAG1 is .83 x rear axle ratio. Typically that is the 3.07 ratio The Charger with the eight-speed ZF automatic transmission compared to the old five-speed NAG1 automatic has 1st gear ratios starting lower at 12.48 vs. 10.99 overall and top out at a higher OGR of 1.78 vs. 2.54 which enables both better performance and better fuel economy. This is why you are at the mileage vs. your girlfriends.

There is some things you can do though that will get you better mileage and more power. The first is ACES IV in the fuel and then switching over to the QuantumBlue Lubricants in all the units....engine, transmission and differential.

We have many Charger owners that have the NAG1 5 speed combination getting 27 to 29 mpg highway. We have the 9 speed in the Chrysler 200 getting 4.5 more mpg than it should be getting simply with ACES IV and the QB engine oils. Cleaner burning, more efficient use of the fuel and less internal friction create this. We have 8 speed 2012 Chargers getting 38.3 mpg on straight long drives. :bigthumb:

Hope this helps.;)

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 

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I have a 12 Charger with the 3.6 and 5 speed. I live in a small town with not much stop and go traffic. I get 20 to 21 MPG in town. When I go to Louisville which is about 50 miles I get about 23 MPG. 70 MPH my RPM is about 2000.
The only mods I have done is mid muffler delete. Why the crappy interstate MPG?
My GF has the same car 1 year newer with the 8 speed her city MPG is a little better. Her interstate MPG is about 30 driving the same speed and road.
As Brian said, definitely gearing and number of gears. I'd routinely average 35mpg+ on road trips with my old '14 3.6 8 speed. Funny story, my '16 5.7 with the 8 speed is getting, and I kid you not, a whopping 32~38mpg average on the highway and if I keep my foot out of it 18~19mpg city assuming no bumper-to-bumper traffic. I think the EPA ratings are way off on these cars for highway mileage.
 

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I have a 12 Charger with the 3.6 and 5 speed. I live in a small town with not much stop and go traffic. I get 20 to 21 MPG in town. When I go to Louisville which is about 50 miles I get about 23 MPG. 70 MPH my RPM is about 2000.
The only mods I have done is mid muffler delete. Why the crappy interstate MPG?
My GF has the same car 1 year newer with the 8 speed her city MPG is a little better. Her interstate MPG is about 30 driving the same speed and road.
In addition to the points noted by Brian and JCE above, it would help for us to understand the maintenance status on your 3.6.

How many miles are on it? Have you changed the spark plugs? How's the air filter? Are your tires properly inflated?

Lots of little things can make a big difference!

My first Charger was a 2012 SE and I was able to get 32-33 mpg at 70 mph on fairly flat roads based on what the display (EVIC) was telling me.
 
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I agree with the maintenance. If you have the stock gears and no mods the gas mpg should be a bit better. Around town I get 15-16 but on the interstate I get 24-26 mpg. We have fairly flat roads. Are your roads to Louisville hilly?
 

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In addition to the points noted by Brian and JCE above, it would help for us to understand the maintenance status on your 3.6.

How many miles are on it? Have you changed the spark plugs? How's the air filter? Are your tires properly inflated?

Lots of little things can make a big difference!

My first Charger was a 2012 SE and I was able to get 32-33 mpg at 70 mph on fairly flat roads based on what the display (EVIC) was telling me.
^ This as well. Great questions here, these things in combination can have a pretty significant impact on fuel economy.
 

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To ecko what JCE said, my 16 5.7 gets in the high 30's per gallon on the highway at speeds up to 70mph no problem. In town it gets high teens to low 20's. Average if I keep my foot out of it is mid 20's, I do about 50/50 city highway.

Not to hate on V6 cars but with the new 8 speed, MDS, and VVT there is no benifit in getting a V6 car anymore other then cost. Which can be a HUGE factor I know.
 

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My 2013 SE V6 NAG1-5 speed in stock form got 18 in town 24 highway (flat road) at 75 mph.

After I installed a Mopar CAI and Dynomax cat back exhaust system it increased to 21 in town / 26 highway at 75 mph.

The highway mileage varies drastically with speed and terrain because of the gearing in the trans and the high 2.65:1 rear axle ratio:

70 mph flat road: 28-29, drops to 26 on hilly roads.
75 mph flat road: 26, only 23 on hilly roads.
80 mph flat road: 23 and a miserable 20 on hills.

Driving on hilly roads between 75 and 80 mph the torque converter is always going in and out of lockup, causing the crappy mileage (I wish it had a 3.07:1 rear axle).

If I keep it between 70-75 mph it runs sweet and gets good mileage, but if you don't go at least 80 mph you get run over by soccer moms in mini vans!
 

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Discussion Starter #9
I agree with the maintenance. If you have the stock gears and no mods the gas mpg should be a bit better. Around town I get 15-16 but on the interstate I get 24-26 mpg. We have fairly flat roads. Are your roads to Louisville hilly?
It is a little hilly
 

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Discussion Starter #10
In addition to the points noted by Brian and JCE above, it would help for us to understand the maintenance status on your 3.6.

How many miles are on it? Have you changed the spark plugs? How's the air filter? Are your tires properly inflated?

Lots of little things can make a big difference!

My first Charger was a 2012 SE and I was able to get 32-33 mpg at 70 mph on fairly flat roads based on what the display (EVIC) was telling me.
My car has about 80,000 miles on it. I change the oil every 5,000 miles. It still has original spark plugs and air filter.
 

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I have yet to find an in car mpg reading that is accurate.
My '14 R/T is AWD with the 5 speed, so I have the 3.06 gears. The best I have seen so far is 21 mpg hwy. I will say that it seems to average right around 20 mpg city/hwy. I don't "stretch its legs out" too often, but when I do I thoroughly enjoy it.

To date, the longest trip was to bring it home from Toledo which was about 150 miles. We are planning a weekend trip to Nashville, TN in the next few weeks, so that will be 500-600 miles round trip of mostly highway.
I will report back with how things go.

Don
 

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My car has about 80,000 miles on it. I change the oil every 5,000 miles. It still has original spark plugs and air filter.
Thanks for that information.

The basic cycle of your engine can easily be described as suck, squeeze, bang, blow.

By using a dirty air filter, the suck part (intake of air) is strained and inefficient. If you're using the original spark plugs, the bang (combustion) where the atomized fuel is burned, is inefficient and incomplete.

There's an article on Challengertalk that describes how to change the plugs on the 3.6 which you can find here:

http://www.challengertalk.com/forums/f108/spark-plug-replacement-3-6l-pentastar-213266/

If you're not up for that, I would have them changed as soon as possible. The air filter is easy and something you can do yourself even if you're not mechanically inclined.

If you have a chance, share some pictures of the air filter (inside the pleats) when you replace it and also take some pictures of the spark plug tips on the old ones.

While this may not fix all of your issues, it's a good place to start.

Please keep us posted.
 

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I am going to have spark plugs and air filter changed
I think that's a good place to start if they haven't been changed before.

Let us know how everything turns out.
 

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Discussion Starter #19
UPDATE
I changed plugs and filter 2 weeks ago. The 1st tank of gas no change in MPG, the 2nd tank in town went up about 1 MPG but trips on interstate went up a lot to about 30 MPG at 70 MPH.
The plugs looked decent but since it was a PITA to get to I changed them, air filter was filthy.
Thanks guys.
 

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UPDATE
I changed plugs and filter 2 weeks ago. The 1st tank of gas no change in MPG, the 2nd tank in town went up about 1 MPG but trips on interstate went up a lot to about 30 MPG at 70 MPH.
The plugs looked decent but since it was a PITA to get to I changed them, air filter was filthy.
Thanks guys.
Glad you got it resolved Dirt.

Now that it's running better there's a couple of other things you can do to keep it that way.

1. Make sure your tire pressures are correct according to the door placard for cold PSI. Make sure you check them first thing in the morning. Under inflated tires can make a mess of mileage.
2. Pick up some throttle body cleaner and remove the throttle body. Spray the throttle plate liberally on the front and back and ensure that it's moving freely.
3. If you want a more permanent air filter that will last the life of the car, consider a replacement such as a Green Filter. These can be washed, are made of denim and don't need to be oiled. Check it every 10k miles and clean it when it shows dirt in the pleats.
4. Consider adding Aces IV to your fuel. This will clean out the intake tract, increase performance by eliminating knock and also increase MPG.

Keep us posted and be sure to reach out if you need a hand!

Cheers,

Andy
 
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