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Dodge Cummins 5.9l or 6.7l MPG?

Discussion in 'Off Topic Threads' started by david, May 13, 2007.

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  1. david

    david Member

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    Gonna buy a new dodge with either the 5.9l or the 6.7l cummins. One of my concerns is fuel economy, I want the one with the best mpg. All the new emission related controls worry me as well as does the new 6 speed auto trans.

    I drove both and the 6.7l seems like a race car compared to the 5.9 and the factory exhaust brake is nice. Trany seemed to work quite well.

    Had a duramax wasnt impressed and dont care for fords.

    Anyone have experience with both? verynx

    David
     
  2. bkeeney

    bkeeney TS Member

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    I own a Dodge with the 5.9 Cummins. I typically get around 18.5 mpg to 22.1 mpg on Hwy between 70 and 80 mph. I do not have it "chipped" but have more than enough power to haul 30-foot RV and Quads. I don't have experience with 6.7's, yet. One thing is for sure I am ex-Ford/Chevy guy and intend to stay that way as long as Dodge has the comfortable ride and power. Just for what it is worth! Good luck.
     
  3. bkeeney

    bkeeney TS Member

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    I should add though I am not getting the above mpg while hauling, obviously. I wouldn't want to open that "can or worms".
    bckeeney
     
  4. GoldEx

    GoldEx Active Member

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    I would have expected better mileage from one of the diesels. My buddy is getting 20 MPG all day long on the highway with a 5.7 hemi in his quad cab 4x4 1/2 ton.

    Jeff
     
  5. PITA ; please move East

    PITA ; please move East TS Member

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    I call B.S. on the hemi getting 20 mpg. I have one and it will not get anywhere close to that. I tried absolutely babying it and not driving over 60 on a trip once and it still only made 17mpg and I was trying every thing to see what I could get for gas mileage. There is no way a person would normally drive the way I did when I was trying to get the best mpg out of it. Under normal driving on the hi-way it usually averages 14-16 with 16 being really flat hi-way.
     
  6. j2jake

    j2jake Well-Known Member

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    It is a safe bet the guy with the Hemi 4X4 getting 20 does not know how to calculate mpg! Pushed over a cliff it will never see 20. My Cummings with a 373 gear gets around 18 hwy no load. With a 5000 lb trailer 10 if I stay in the 70s. Over that its 7-9, City its 12 -14. Truck has 48000 mi. and those are real numbers. Jake Oh yea its a two wheel drive.
     
  7. Texas Ton

    Texas Ton TS Member

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    The Hemi will get 20-------if you put it on a trailer behind the Cummins ;^) and leave it idling.
     
  8. LUGNUTZ426

    LUGNUTZ426 TS Member

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    My hemi gets 19 on a straight flat run, in warm weather. It is the newer design with the MDS system. This was only added to trucks last year. It adds 2 to 3 mph
    moderate cruising speeds with light loads. Rear axle ratios, tire type/pressures make a difference too.
     
  9. PITA ; please move East

    PITA ; please move East TS Member

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    I call B.S. on the hemi getting 20 mpg. I have one and it will not get anywhere close to that. I tried absolutely babying it and not driving over 60 on a trip once and it still only made 17mpg and I was trying every thing to see what I could get for gas mileage. There is no way a person would normally drive the way I did when I was trying to get the best mpg out of it. Under normal driving on the hi-way it usually averages 14-16 with 16 being really flat hi-way.
     
  10. j2jake

    j2jake Well-Known Member

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    It is a safe bet the guy with the Hemi 4X4 getting 20 does not know how to calculate mpg! Pushed over a cliff it will never see 20. My Cummings with a 373 gear gets around 18 hwy no load. With a 5000 lb trailer 10 if I stay in the 70s. Over that its 7-9, City its 12 -14. Truck has 48000 mi. and those are real numbers. Jake Oh yea its a two wheel drive.
     
  11. Texas Ton

    Texas Ton TS Member

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    The Hemi will get 20-------if you put it on a trailer behind the Cummins ;^) and leave it idling.
     
  12. LUGNUTZ426

    LUGNUTZ426 TS Member

    Joined:
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    855
    My hemi gets 19 on a straight flat run, in warm weather. It is the newer design with the MDS system. This was only added to trucks last year. It adds 2 to 3 mph
    moderate cruising speeds with light loads. Rear axle ratios, tire type/pressures make a difference too.
     
  13. thewolf

    thewolf TS Member

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    Jun 27, 2006
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    I've had both. Most important, gearing. On the window sticker or if used on the front underside of the hood. 3.54 would be nice. I've never seen a 6.7 with 3.54, only 3.73. Unless you are towing something obscene, no 4.11. If you can stand it, manual gearbox. The power is just used better. With the torque these things have you don't shift too often. I can go from PA to OK in top gear. Also, if you don't need it, don't get 4wd. Its like wearing a winter coat all year in case it snows. Might want to look at a used 5.9. I've put 250k to 300k on 3 of them. They don't break very often. The older auto trannys 1994-2004 are terrible. For about $3000 you can get a real good one. Check out turbodieselregistry.com. Its an all Dodge website. Click on discussion forum and lose 2-3 hrs.
     
  14. thewolf

    thewolf TS Member

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    I've had both. Most important, gearing. On the window sticker or if used on the front underside of the hood. 3.54 would be nice. I've never seen a 6.7 with 3.54, only 3.73. Unless you are towing something obscene, no 4.11. If you can stand it, manual gearbox. The power is just used better. With the torque these things have you don't shift too often. I can go from PA to OK in top gear. Also, if you don't need it, don't get 4wd. Its like wearing a winter coat all year in case it snows. Might want to look at a used 5.9. I've put 250k to 300k on 3 of them. They don't break very often. The older auto trannys 1994-2004 are terrible. For about $3000 you can get a real good one. Check out turbodieselregistry.com. Its an all Dodge website. Click on discussion forum and lose 2-3 hrs.
     
  15. thewolf

    thewolf TS Member

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    Also if you need more power. For $500 or so you can got another 100hp out of these things. The new programmers are incredible. Used to have to do injectors, turbos, fuel pumps, fuel plates, and governer springs. Now just plug in and go. Some even save your stock program for when she goes back to the dealer.
     
  16. MX/MT

    MX/MT TS Member

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    I have the Dodge 3500 CTD 5.9L w/48RE tranny, 4x4, 4:10 and I get 12 mpg towing a 14,000 lb. fifth wheel. 18-20 unloaded on the highway.
     
  17. david

    david Member

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    Anyone know if the mileage between the 5.9 and 6.7 is the same, worse, better etc? How much worse if worse?

    Thanks you all the replies keep them coming.

    David
     
  18. thewolf

    thewolf TS Member

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    Just over at the TDR. 6.7 owners complaining of poor mileage. 13-14 mpg is typical. No suprise, bigger displacement and way more emission controls including egr(exhaust gas recirculation). With the exception of the built-in exhaust brake, I'm just not seeing the progress of the 6.7. It seems they have taken a good product and meddled it too much. Hell, my 95 2wd dually got 18mpg and is still on the road with over 300k. It has over 300hp and no major comp failure. Progress may be regressing. To answer your question. All things being equal, for mileage only, the 5.9. All things are never equal so buy which ever one appeals to you or, if your like most of my friends; Whichever one the wife liked the day you went to the dealer.
     
  19. GoldEx

    GoldEx Active Member

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    MDS Hemi, Bighorn package with 20" pretty boy wheels and street tires. Driving it like a white man and yes, it does get 20 all day long in 2wd on the freeway. My dad's Dakota 4.7 V-8 4x4 gets almost 23 if he keeps it at 65.

    Jeff
     
  20. DB3006

    DB3006 Member

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    As for mileage you can expect to get anywhere from 15 to 19 mpg on the highway with no load from any of the big three(GM,FORD,DODGE). I work for a Diesel fuel injection shop in Wisconsin and have heard every story. From 28 mpg from a Duramax to 6 mpg from a Dodge. Most do not know how to due the caculations or are relying on the trip comp in the truck.

    AS for the new 6.7 I would give it a year to prove itself before buying one.

    Dave
     
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