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Thread: Mpg

  1. #1
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    Mpg

    I have a 06 R/T AWD Hemi and man do i get some terrible MPG i mean like 10 in city and mayb 15 on highway. It has about 75K and is plain old Stock i have been putting 87 Octane cause the manual says to put that in. But what can i do to get better MPG since summer is here and i want to go down to the shore and fish.



  2. #2
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    87 Octane is not recommended for the 5.7 Hemi, it calls for 89 or higher. This is not likely the cause of your low mpg though, rather just costing you a bit of power as the timing will be retarded automatically. A lot of MPG has to do with driving habits and will be significantly lower under hard driving styles and if you spend a lot of time idling (0mph with car running = 0 mpg). AWD will always have a little lower MPG than RWD as there is more parasitic loss in the drive train as well. Things to look for or check would be some simple maintenance items. When was the last time the plugs were changed? The 5.7 runs copper plugs that are recommended to be changed at 30,000 mile intervals. Should be able to pull a couple and visually inspect them. Also you may want to make sure your MDS is working properly. While not a huge gas saver, it will contribute up to 10% or so increase in MPG. Also, are there any stored CEL codes? There are a myriad of sensors that can wear out over time and if not working properly could lead to deterioration of MPG.

    Also, don’t rely solely on the computer to provide you MPG number. How many miles are you getting per tank (city and highway)? Have you had any full tank highway runs that might allow you to more accurately calculate your highway mpg. Also a small difference in highway speeds can make a big difference in mileage. The MDS will only operate at up to 20% pedal pressure or lower and will likely drop out around 65mph. I also notice a moderate headwind at highway speeds can cost me up to a couple mpg (tailwind will conversely increase it).

    All that being said I’ve talked to plenty of AWD guys that routinely pull 19-20 mpg highway with stock setups. The 10-15 you report does sound low, so I would start checking a few of the things mentioned above. GL
    2005 MRT, CV, K&N CAI, 20" Black Powder Coat CSRT OEM Wheels

  3. #3
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    I only get 18 in my RWD R/T. I actually told my wife when we maybe the car we would get in the low 20's. I ran 89 and just changed my spark plugs about 4,000 miles ago.
    2003 Dodge Ram 2500 Hemi
    2005 Dodge Magnum R/T Hemi

  4. #4
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    27mpg with bosche +4 platinum on CRIUSE. Get you foot out of it and it will give you the advertised mileage. Oh yeah, mine is broken in well...
    05 Magnum RT 5.7 (Member ALLPAR.com 200,000 mile club) Rockinsrt8 shifter, Hemi reg #164 325,000 miles
    Sidewinder, 6.1 pushrods, springs, underdrive pulley, SRT exhaust (donated by NHDave) headers to tips, all installed by Hemi31! Quaife, certain Pedders bushes installed, SRT Nivomats and Bilsteins. Police rotors and pads. HIR. Predator. LMI.

    09 Jeep GC Limited, Hemi powered of course.

    1:19 NJMP Lightning
    1:45 Mosport

  5. #5
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    May 2012
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    We just did a round trip to vegas, about 600 miles. When we got home the MPG was at 20.6
    She's got 70K miles (As of the way home) fresh plugs, oil changed at 69K, clean and freshly oiled CAI filter , I pulled fuse 11 2 weeks ago, Tire pressures all set and cruise on 70-80.
    Not too bad. I'm ok with it.
    2005 Magnum R/T, Mopar CAI, Mopar Strut Brace, Eibach Springs, Flowmaster 40's, Custom Grill, Debadged, 22" DUBs others...

  6. #6
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    Easy 30+mpg on the HWY for me. there are lots of threads if you search.
    Just lurking. Hemi Registry #1050

  7. #7
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    Quote Originally Posted by Coopers_Dad View Post
    Easy 30+mpg on the HWY for me. there are lots of threads if you search.
    I hear these 30mpg claims, but never seen anything close even with all highway mild speed driving. Is it in the tune??

  8. #8
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    Unfortunately it is in the left foot more than anything else, its FLAT here, no way to do it otherwise...

  9. #9
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    Quote Originally Posted by mike777 View Post
    I hear these 30mpg claims, but never seen anything close even with all highway mild speed driving. Is it in the tune??

    You? Drive mild? Hahahahahhahahahahaha! Since when?



    I typically average 18~22 with a 50/50 city/highway drive. On long trips, I've hit upper 30mpg range a few times (trip from MN to TX and back, trips where I can set cruise and drive one constant speed for 75 miles or more).
    2006 Charger Daytona - Show&Go
    2013 Ram 1500 Express - Snow&Go
    "When you do things right, people won't be sure you've done anything at all."





  10. #10
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    Mar 2012
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    I used to get around 28 highway and 24 city, but those days are long gone. I don't slam on the gas very often, but when I do, it eats up the gas. Luckily, when I replace the EGR and plugs, it'll go a little bit better.
    New plugs, coilovers, fuel rails, EGR valve/pipes. Brake, tie rods, and updated PCM.

  11. #11
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    Apr 2010
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    I have 95k.
    I'm running the 91 octane tune via flashpack.
    My daily commute is 13 miles, 10 of it in highway each way with traffic (40-50mph) in the morning, and similar back but some of it is stop 'n go.

    I average 17 mpg overall via evic.

    I recently changed plugs again to champions, other than 6.1 stock intake the car is stock.
    I am easy on the throttle. Chicago has some sucky gas but I think now we are well into the summer tune gas here (it's crazy, in the chi metro we get crappy winter gas). and get this. in season change there is always shortage and price goes up (but it does not go down after the switch over).

    I recently changed the crankshaft position sensor and my motor has no codes.
    When I got the car at 67k or so I had much better MPG but soon after I had plugs changed due to misfire, since then I've never had good MPG (and I recently had plugs changed again).

    it sucks.

  12. #12
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    My AWD R/T averages 50/50 highway/city about 16-17.5 mpg. I'm lucky to get over 20 on all highway.
    2005 Magnum RT AWD 344AWHP/358AWTRQ
    FRI Sidewinder Cam, Johan Tune, Edelbrock Headers, JBA Hi-Flo Cats, Magnaflow Catback, 180* T-stat, aFe Stg II CAI, 85mm Throttle Body, SLP 25% UDP, Catch Can, Taylor Shortys, Freak351 Trans Box , Eibach Pro Kit Springs & R1's. Interior, Engine & "M" Emblems by Billet Tech, R/T Emblems, Magnum R/T Grille, Black Heads & Tails, Eyelids

  13. #13
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    Hmm. I ended up having to replace the throttle body twice and the fuel rails once so far. Too bad the stealership didn't cover it because I was still in my first year of ownership. My mpg has stayed relatively the same if I drive highway, but I don't do a whole lot of driving in the city anymore: mpg drops like a stone to around 12-13 - yeesh.
    Next major mod besides the ones I need to do is a major tuneup. Gotta get some money first though :(

  14. #14
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    Hey folks, don't forget to FLOG it once in a while! It REALLY makes a difference. From 5mph to the first second shift, EVERY day ONCE.

  15. #15
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    Also ^ Easy 30MPG for me on cruise.

    Before I changed my EGR Valve, MDS Mode was NOT engaging, resulting in TERRIBE Gas MPGs....
    2005 Magnum R/T- Gone but not forgotten
    2013 Dart Rallye Turbo - Gone
    13' Mazdaspeed3 tech pkg/03' Durango SLT+AWD - ​Current
    06'Cobalt SS(s/c)/96' Explorer/13' Civic - Current
    16' Challenger RT Shaker Sublime Green - Ordered

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