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6.7 Fuel MPG
- Thread starter KSHall
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Here is my experience, With the stock tires on flat Florida I get 14 mpg average, with 75% draging 12K / 25% empty suburban & country roads. My best was the first 500-600 miles to home from the dealership mostly all I-75 southbound, averaged 17 mpg.
When I went to the bigger tires I lost 2 mpg, at 7k I've earned 1 mpg back.
I can say this my mileage is better than I got with my 05, It started at 10 mpg and was up to 20. 03 empty (combined / towing average 16 mpg) at 23 months / 80k. They take way longer to loosen up than anyone admits!
Both trucks never more than 4 hours from home, so no long trips.
When I went to the bigger tires I lost 2 mpg, at 7k I've earned 1 mpg back.
I can say this my mileage is better than I got with my 05, It started at 10 mpg and was up to 20. 03 empty (combined / towing average 16 mpg) at 23 months / 80k. They take way longer to loosen up than anyone admits!
Both trucks never more than 4 hours from home, so no long trips.
My truck has not gotten away from 15mpg regardless of driving conditions. That is less mpg empty than my '99 got pulling a 7K trailer. Thankfully, the dealer service manager is taking this seriously. DC told him I need to get more miles on the truck, to which he told them, "that won't make a difference". DC's reply was - your right, but it will buy us more time. The service manager's thought is they have the regen's set too often (to get max life from DPF). It is obvious to him and I there is an issue here - it is only a matter of how to deal with it (reprogram the computer, perhaps?). If DC does nothing, I will be looking for a chip that is compatable with the 6. 7 emission equpment.
This confirms what I suspected. While towing heavy, there is enough heat in the exhaust to keep the catalyst and the regen cycle hot enough, so there will be a minimal penalty on MPG.
Empty, there is a severe penalty, since it needs to throw fuel out the tailpipe very often just to keep the cat/filter hot. It has a throttle plate on the inlet that they use to limit air intake and heat up the exhaust.
Empty, there is a severe penalty, since it needs to throw fuel out the tailpipe very often just to keep the cat/filter hot. It has a throttle plate on the inlet that they use to limit air intake and heat up the exhaust.
I just got back from another 222 mile trip to Grand Junction from Basalt, and again kept the cruise control on 62 mph. I try to keep the tach at 1500 rpms, since that seems to be this truck's "sweet spot," and I had the AC running the whole way, too.
My Ram has a heavy ARB bumber, a WARN 16,000 winch set-up, and an "Extendo-Bed" in the rear. The Extendo Bed, itself, weighs about 500 pounds, so I know I've added at least half a ton to this truck's standard "dry weight".
In addition, I've got my normal compliment of carpenter's tools, surveying equipment, parts bins, etc. already on board.
The ARB is a pretty slick set of "bull-bars," but I know it's not the most aero-dynamic set-up.
My dually got ("hand-calc'd") 16. 45 on that round trip, and an almost identical 16. 28 on a round-trip from Denver earlier in the week. This is high-altitude mountain driving, which has got to be less than ideal for the purposes of fuel-efficiency, and the truck now has about 2800 miles on the clock.
Somebody else mentioned this, but I think that one of the reasons our overhead read-outs tend to be a little "optimistic" (snort, cough... ) is that the odometers tend to read a little faster than we're actually traveling, and thus they read more miles than we're actually traveling.
I'm using my GPS unit to do all the calculations. When my speedometer is reading 65 mph, I'm actually traveling about 62-63 mph. The cynical side of me could easily be persuaded to conclude that this slight "fudging" causes our trucks to go out of warranty several months sooner than they normally would and, thus, saves the bean-counters at Chrysler a few million (or, whatever... ).
Somewhat annoying, also, is the fact that the overhead display is wildly inaccurate: Mine told me that my "average mpg" on the Denver round-trip was 18. 2 mpg, so it was off by 2 mpg. Percentage-wise, that's pretty far from the mark -- far enough off to make referring to this readout pretty pointless.
Still, all-in-all, 16-17 mpg on a very heavy truck during its break in is something I'm more than satisfied with, for now.
I guess I'll be one of the guys (once the bugs are worked out) lining up to chip my rig -- and not for the horse-power increase, but to make whatever timing and other engine CPU adjustments are necessary to make driving this truck as economical as possible.
My Ram has a heavy ARB bumber, a WARN 16,000 winch set-up, and an "Extendo-Bed" in the rear. The Extendo Bed, itself, weighs about 500 pounds, so I know I've added at least half a ton to this truck's standard "dry weight".
In addition, I've got my normal compliment of carpenter's tools, surveying equipment, parts bins, etc. already on board.
The ARB is a pretty slick set of "bull-bars," but I know it's not the most aero-dynamic set-up.
My dually got ("hand-calc'd") 16. 45 on that round trip, and an almost identical 16. 28 on a round-trip from Denver earlier in the week. This is high-altitude mountain driving, which has got to be less than ideal for the purposes of fuel-efficiency, and the truck now has about 2800 miles on the clock.
Somebody else mentioned this, but I think that one of the reasons our overhead read-outs tend to be a little "optimistic" (snort, cough... ) is that the odometers tend to read a little faster than we're actually traveling, and thus they read more miles than we're actually traveling.
I'm using my GPS unit to do all the calculations. When my speedometer is reading 65 mph, I'm actually traveling about 62-63 mph. The cynical side of me could easily be persuaded to conclude that this slight "fudging" causes our trucks to go out of warranty several months sooner than they normally would and, thus, saves the bean-counters at Chrysler a few million (or, whatever... ).
Somewhat annoying, also, is the fact that the overhead display is wildly inaccurate: Mine told me that my "average mpg" on the Denver round-trip was 18. 2 mpg, so it was off by 2 mpg. Percentage-wise, that's pretty far from the mark -- far enough off to make referring to this readout pretty pointless.
Still, all-in-all, 16-17 mpg on a very heavy truck during its break in is something I'm more than satisfied with, for now.
I guess I'll be one of the guys (once the bugs are worked out) lining up to chip my rig -- and not for the horse-power increase, but to make whatever timing and other engine CPU adjustments are necessary to make driving this truck as economical as possible.
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I have been keeping track of my fuel milage sence I recived my truck about 6 weeks ago. It seems that my hand calc's are always about 1 to 1. 5 MPG less than my overhead. Most of my trips are on the freeway cruse control set at 73 MPH. 200 Miles to work one way. Here is what I got on the 7, I calced. 1st-13. 94, 2nd-13. 95, 3rd-13. 46, 4th-15. 07, 5th-13. 15, 6th-14. 33, 7th-15. 2 .
I think the biggest reason why I'm getting a little better mileage, overall, is that I'm cruising about 10 mph less than everyone else. My speed on the highway is always about 60-62. That's definitely worth a couple miles per gallon, which is why I'm getting high 16s, low 17s.
There's a big mpg penalty -- it seems to me -- for pushing these rigs over 70 mph.
As others have pointed out, advancing the timing should help a lot. That's the biggest reason I'm looking forward to a "reprograming" chip-set from our after-market guys. If they can figure out a safe way to advance the timing and boost fuel-efficiencies without messing up the exhaust system, I'm an eager buyer.
There's a big mpg penalty -- it seems to me -- for pushing these rigs over 70 mph.
As others have pointed out, advancing the timing should help a lot. That's the biggest reason I'm looking forward to a "reprograming" chip-set from our after-market guys. If they can figure out a safe way to advance the timing and boost fuel-efficiencies without messing up the exhaust system, I'm an eager buyer.
can't wait to see what people are getting once broken in. I still haven't seen a 6. 7 yet around here, the last of the 5. 9s 
Sasquatch
Your Diesel is turbocharged so altitude does not play much of an effect on its ability to make power. It should get the about the same mileage at 6000 ft as it does at sea level.
Fred
Your Diesel is turbocharged so altitude does not play much of an effect on its ability to make power. It should get the about the same mileage at 6000 ft as it does at sea level.
Fred
Fred,
I've read all the arguments about air-density at altitude and am more confused, now, than I was to start with.
What I do know, for sure, is that I noticed a marked decline in mpg when I moved to the mountains from the southeast. I put a quarter-million miles on my '97 turbo diesel, and could tell you -- within half a mile per gallon -- what sort of fuel efficiencies I was going to see, depending on where I drove (city/highway), and what speed I was driving at.
When I moved to the Roaring Fork Valley (I live at closer to 8,000 ft), I noticed an across-the-board (under any driving scenario) drop in efficiency of anywhere between 15-20%.
My "city driving" mpg (stoplight to stoplight) dropped from about 14 mpg down to 11-12, and my "highway" from 18-19 down to 15-16.
One thing you experience when driving in the mountains (that you don't typically experience at sea level) is that you're almost always driving on an incline: The truck is always laboring up a hill or coasting down a hill: This makes for bad fuel-economy, regardless of the altitude number.
At least that's been my experience.
I've read the learned, physics-based arguments ("flame wars") engaged in by guys who live in the mountains, vs "flat-landers," and I can also bear witness to the fact that our turbos don't make the boost at altitude that they do at sea-level. Less boost, intuitively, would seem to mean less horsepower, which would seem to translate into less performance, and less mpg.
But, I'm not a physicist, so my "empirical" observations could be about as accurate as the guy who reasons -- through observation, alone -- that the moon is made outta cheddar cheese.
It's Gouda, right?
I've read all the arguments about air-density at altitude and am more confused, now, than I was to start with.
What I do know, for sure, is that I noticed a marked decline in mpg when I moved to the mountains from the southeast. I put a quarter-million miles on my '97 turbo diesel, and could tell you -- within half a mile per gallon -- what sort of fuel efficiencies I was going to see, depending on where I drove (city/highway), and what speed I was driving at.
When I moved to the Roaring Fork Valley (I live at closer to 8,000 ft), I noticed an across-the-board (under any driving scenario) drop in efficiency of anywhere between 15-20%.
My "city driving" mpg (stoplight to stoplight) dropped from about 14 mpg down to 11-12, and my "highway" from 18-19 down to 15-16.
One thing you experience when driving in the mountains (that you don't typically experience at sea level) is that you're almost always driving on an incline: The truck is always laboring up a hill or coasting down a hill: This makes for bad fuel-economy, regardless of the altitude number.
At least that's been my experience.
I've read the learned, physics-based arguments ("flame wars") engaged in by guys who live in the mountains, vs "flat-landers," and I can also bear witness to the fact that our turbos don't make the boost at altitude that they do at sea-level. Less boost, intuitively, would seem to mean less horsepower, which would seem to translate into less performance, and less mpg.
But, I'm not a physicist, so my "empirical" observations could be about as accurate as the guy who reasons -- through observation, alone -- that the moon is made outta cheddar cheese.
It's Gouda, right?
Sasquatch
Because a turbo cannot change it's boost ratio like a supercharger can change drive pulleys to increase boost due to lack of air density you are somewhat correct. As with all things that spin and heat and cool turbochargers loose clearance and perform less as they get older and this can only be compensated for by either refurbishing or installing a new and larger turbo, but that is a whole other set of problems. It's all about therms per power cycle.
Fred
Because a turbo cannot change it's boost ratio like a supercharger can change drive pulleys to increase boost due to lack of air density you are somewhat correct. As with all things that spin and heat and cool turbochargers loose clearance and perform less as they get older and this can only be compensated for by either refurbishing or installing a new and larger turbo, but that is a whole other set of problems. It's all about therms per power cycle.
Fred
Mileage
Just filled up tonight, 405. 8 miles and 29. 8 gallons for an average of 13. 62. This was driving 20 miles to work each way each day with a normal amount of stop and go and no freeway driving. The tank before this was right at 17 but that was a lot of highway driving with very little stop and go. The low fuel light came on as I was pulling up to the pump and the fuel gauge was reading just above the red mark. Still had about 5 gallons of fuel in the tank if it's indeed 35 gallons.
Just filled up tonight, 405. 8 miles and 29. 8 gallons for an average of 13. 62. This was driving 20 miles to work each way each day with a normal amount of stop and go and no freeway driving. The tank before this was right at 17 but that was a lot of highway driving with very little stop and go. The low fuel light came on as I was pulling up to the pump and the fuel gauge was reading just above the red mark. Still had about 5 gallons of fuel in the tank if it's indeed 35 gallons.
TK,
Seems reasonable to me, to tell you the truth. If I'm getting 14-15 in town and 17-18 on the highway while driving one of these beasts (before it's broken in), I'm basically a very happy camper.
My '97 didn't do much better, and it didn't have all the bells and whistles this baby has. Forget about the engine brake, which is icing on the cake: This truck has superior service brakes, great transmission, power driver's seat, overhead display, great towing mirrors, and the list goes on.
I paid $33,000 for my '97 2500 4x4 (and thought I was getting a fairly good deal) and about $6,500 more for my '07 3500 4x4.
When I consider what the cost of living has done in those intervening 10 years, it seems to me we're getting a hell of a solid value with these trucks.
Getting another couple of mpg would be nice -- and I'll opt for the "chip solution," when it's available -- ('cause fuel prices ain't goin' down... ), but, in the meantime, I'm very satisfied with my new ride and its fuel economy.
Seems reasonable to me, to tell you the truth. If I'm getting 14-15 in town and 17-18 on the highway while driving one of these beasts (before it's broken in), I'm basically a very happy camper.
My '97 didn't do much better, and it didn't have all the bells and whistles this baby has. Forget about the engine brake, which is icing on the cake: This truck has superior service brakes, great transmission, power driver's seat, overhead display, great towing mirrors, and the list goes on.
I paid $33,000 for my '97 2500 4x4 (and thought I was getting a fairly good deal) and about $6,500 more for my '07 3500 4x4.
When I consider what the cost of living has done in those intervening 10 years, it seems to me we're getting a hell of a solid value with these trucks.
Getting another couple of mpg would be nice -- and I'll opt for the "chip solution," when it's available -- ('cause fuel prices ain't goin' down... ), but, in the meantime, I'm very satisfied with my new ride and its fuel economy.
Just picked up my 6. 7 CTD from Dishman Dodge and drove it 1180 miles back home. On the first 2 fuel fills, I got just over 17 MPG. This was after driving at different speeds for the first 500 miles as recommended on several TDR posts. On the third fill, after driving 400 miles at a steady 75 MPH, the mileage dropped just slightly to 16. 87 MPG. The engine had 11 miles on it when the trip began. For what it's worth.
rcelum
rcelum
gsbrockman
TDR MEMBER
Well, just got my first tank of ULSD ran thru the Blue Bird Bus. :-laf
The overhead said 15. 7 avg mpg... ... hand calculated, it ended up being 14. 6 mpg.
I'll give it a second fill-up before I decide if it's to be or not. I'm quite sure the dealer didn't fill it up the way I normally do. My best fuel economy didn't hit until around 20k miles on my past three CTD's, too..... I think I need to throw the wife's JEEP Liberty on the car hauler and find some hills to accelerate break-in.
462. 3 miles / 31. 683 gals = 14. 6 mpg.
462. 3 miles and 11:52 = 38. 957 avg mph.
Casper (my 2003 RAM 2500 Crew Cab 4x4 305/555 NV5600) could always easily go 550+ miles before the low fuel light came on.
Greg
#ad
The overhead said 15. 7 avg mpg... ... hand calculated, it ended up being 14. 6 mpg.
I'll give it a second fill-up before I decide if it's to be or not. I'm quite sure the dealer didn't fill it up the way I normally do. My best fuel economy didn't hit until around 20k miles on my past three CTD's, too..... I think I need to throw the wife's JEEP Liberty on the car hauler and find some hills to accelerate break-in.
462. 3 miles / 31. 683 gals = 14. 6 mpg.
462. 3 miles and 11:52 = 38. 957 avg mph.
Casper (my 2003 RAM 2500 Crew Cab 4x4 305/555 NV5600) could always easily go 550+ miles before the low fuel light came on.
Greg
#adThe mileage was hand calculated. The trip computer read 19 to 19. 5 for the same miles, over 2 MPG more than the actual mileage. I used my cruse control to vary the speed for the first 500 miles, never much less than 60 or over 75 MPH. I thought that 17+ MPG was not bad for a new engine but now have hand calculated another 320 miles doing a steady 70 MPH and only got 14. 36 MPG. So it's hard to tell what the mileage will be after the engine has been well broken in.
rcelum
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