I just want to know which diesel engine will get the best MPG. Old or new , Ford or GM. What upgrades would help with MPG.I have talked to a few people who have trucks for sale and I get the feeling they are pulling my leg or trying to make a sale with tall tales of 24 mpg. I perfer the look of the new Ford F350 sd 4 door 4X4 but am open to what ever will produce the best MPG. I have to act fast or else I will end up driving a mini van (wifes idea 20 mpg). Please send coments to me at welj31@netzero.net Thank you:help:

First of all welcome to the forum. I have experienced continuously with my Dmax around 18MPG in town and last weekend took a trip from Tucson to Flagstaff Arizona all up hill and got around 20MPG all freeway and 23MPG on the trip back. I have 31K on my 2003 and it consistently gets this mileage with my Juice no Attitude set on Level 3. When towing my 38' 5ver @ 12K I get around 10-11MPG with Juice on Level 2 and Allison Tranny in Tow/Haul...My $.02..Jim

05 gmc 16,000 miles 15-16mpg

03 GMC 47,000 mi 16 mpg with 90% stop and go, 21-22 on the highway at 70 mph ave speed. Both averages are empty.

thanks for the info how bout the older trucks 91 to99

And how about you Ford guys? Speak up and help convert me ( I have had 22 Chevy/Gmcs). Also has anyone tried to convert a older GMC (86) to diesel from gas and if so what was the job like as far as skill level and cost. I have a 86 GMC sub 3/4 ton 4X4 and I love the truck but I live in a remote area nearest store is a 80 mile round trip so @ 8 mpg the cost is just to much.

I may be able to help since I have had or worked out of most the diesels on the market. We will start with the Fords. The 6.9 gets around 15 mpg in an E-350, I had a 7.3 before the turbo in a box truck it got 9 mpg, have had 2 7.3 power stroke in the newer Ford 250's both 4x4 one x cab one crew cab both auto. Both trucks got around 18 mpg unloaded and 10-12 with 6,000 behind them. Neither truck made it past 30,000 miles with out major work on them. Next we will go to the new Dodge. i had an 03 H.O. with a 6 speed 4x4 quad cab. Empty the truck would get around 20 mpg on the hwy at 75. Pulling 6,000 -11,000 it would get 12 MPG at 70. Got rid of the truck because I had trouble with the dealers around my area. Traded the Dodge for my current 05 crew cab 4x4 GMC. With 10,500 on the truck it gets around 10 MPG pulling 6,000- 11,000 pounds. I have only ran one tank unloaded and it was 20 MPG at 70. I really did not expect to get that out of the truck I was hopping for 17 MPG. My current Chevy box truck gets 9 MPG. I have recently acquired an 1995 Dodge 12v Cummins 4x4 5 speed and it is getting 21 MPG with 117,000 on the ticker. pulling the 6,000 lb trailer it is getting 17-18.
What does all this mean. If you are looking for MPG I think I would go for an old 2nd gen dodge with a 12v Cummins. If you do this I hope you have some mechanic skills because the Dodge part is not great.
Hope this helps.
Tom.

I can concur the pre 2004 dodge diesels do very well on fuel. 24mpg? someone is pulling your leg.

So much depends on how you drive it. These things can do very well or they can get very poor mileage. 1 or 2 stomps on the gas can kill your average per tank. My mpg unloaded is usually somewhere between 17.5 and 19 depending on conditions.

For trucks built after jan 2004, i'd say that all have the same mpg potential

i have a 05 duramax it gets 18 to19 interstate when i hook to my camper i get 8 to 10 mpg at 72 mph i hope it gets better. i was told from some people i should see 13 or 14 pulling my camper the only way i might see that if i go probly around 50mph. i hope it gets better.

I would lilke to thank everyone for their in put. As for the DODGE thing I might have to find a wreck and pull the motor(12) the last two I had to sell for $100. and make the buyer take the other one with it just to get it out of my yard. The engines ran fine but everything else was junk.

welj31,

What do you intend to do with this high mpg truck? I had an individual in an OK truck stop take extra time to rub my nose in how his 76 VW pick-up, with an 79 rabbit diesel engine swap, got 36 or more mpg on the highway..... Frankly, his 1/2 primerred, bumperless, day-glow green and lemmon yellow prized diesel looked like a POS with a Clinton/Gore bumber sticker for a tail-gate. Beauty is indeed in the eye of the beholder.

Those that buy diesel work trucks to haul heavy loads for a living or recreation seldom quibble on mpg, since it is a contious decision to forgoe green-peace and operate on the highway safely and economically (where time is money). It is also important to have the ability to operate these working trucks whenever needed and not have to replace them before the base warranties run out. For many of us, every day off work waiting for the truck to get out of the shop is a day without pay, whether its for a problem with the engine, drive-train, brakes, chassis, or sheet-metal.

Stating your intended use clearly would help us guide you in the direction you would like to go.

RF

I just got 14 MPG on a 2100 mile three day round trip in my 1993 k2500 with a 6.5 The entire trip took only 58 hours, including 3 hours down time waiting to pick up the boat I went to get. 14 sounds low, but I set the cruise control at 80 miles an hour, and stayed there hours on end. Half the trip was towing an 1800 lb boat, and carry an extra 110 gallons of diesel. Diesel is now $3.17 per gallon in California, and I got it for $2.39 in Denver. Expecting lower prices, I took 2 empty 55 gallon drums. A good call!

My 05 Duramax with only 900 miles mostly around town is getting about 14 as well. I expect it to get better with age and on the open road.

I've been reading these threads for a while and my interest too is MPG.I have come to the conclusion that all you can do is get better air flow,better exaust,cleaner fuel(dual filters) and no not even a chip or tuner will help enough to ever pay for itself.I was going to get a chip or tuner for my D/A but talked to a guy that worked in a shop who had the same rig but had added a 5"exaust,K&Nair filter,chip,etc.and he claims to have gained 1mpg.How much diesel will that buy?

with my 6.5 I get about 15-16 mpg back and forth to the office from the ranch. (12 miles , 3 gravel and rest 2 lane and 2 miles in town. On the hiway at 75 mph 19.5-20.5

Just returned from our trip to Alaska. We have a 2002 LB7 with 61000 miles after the trip. We towed a 10,000 lb 5th wheel and traveled 11,137 miles, all with the Juice set on level 2. Our total average was 11.29 MPG over some of the worst roads you will ever encounter (but a great trip). Traveling empty on the Interstate on level 4, we will average 20 - 21 MPG.
Stubby

BigChief just about hit the nail on the head! ;) The mods being implemented on the overheating thread are yielding some pretty impressive mpg improvements, both cruising and towing. Cold air intake, sealing around the stack and venting underhood temps along with a free flowing exhaust appear to be the right prescription for unleashing the power in these trucks.

Once we have more permanent materials in place for these mods we'll post them on the forum for all to consider. Towing at 24K lbs my truck has improved from 8-9 mpg to ;) 10-11 mpg. This will likely get better once I install a cold air intake and vent underhood heat.

The 06's appear to have implemented several of these mods already. If buying new it would be my top choice right now. Later. JJ :)

On vacation that monday my 2000 Ford f250 4x4 auto 3.73 gears empty from Ennis Mt. to Cody Wy. 231 miles one way used 11 gal and coming back used 11.5 gal. that is my best. That's going through Yellowstone.

98 k3500 L65 4x4 crew 4.10 gears: Best ever was 22mpg (interstate run), average 19mpg. Reckon my average is around 18...

i have a 03 duramax cc 4x4 with 4inch exhaust, bullydog power pup set on 95 horse all the time and a tst powermax comp chip, airraid intake, bullydog trans kit, 285-75-16 tires. running empty I run the tst chip in set 2 .In town I get 17 to 18 mpg all the time, empty highway I get 24 to 25. Pulling my enclosed 20 ft car trailer with my 67 prostreet nova inside I get around 14 to 17 depending how many hills or grades I have to climb, but pulling I cant have the tst chip on or it will throw a code.

16 mpg empty best so far. Average is 14.5 empty. Towing/hauling car trailer and equipment 11mpg approx 8000lbs . I have 13k miles and sure hope it gets better I drive like an old lady 99% of time cuz I hope this truck last as long as my last truck. 30mpg sounds like a pipe dream to me

I can concur the pre 2004 dodge diesels do very well on fuel. 24mpg? someone is pulling your leg.

So much depends on how you drive it. These things can do very well or they can get very poor mileage. 1 or 2 stomps on the gas can kill your average per tank. My mpg unloaded is usually somewhere between 17.5 and 19 depending on conditions.

For trucks built after jan 2004, i'd say that all have the same mpg potential
i got 23 with mine, when i was going about 60 with the stock tires.

I traded a 96 Dodge extended cab for the truck in my sig. The old truck was 2wd, 4.10 rear end, and manual tranny. Empty I consistently got 21.5 mpg on the highway and 20 combined. The 4.10 read end made towing the 5th wheel pretty easy but hurt the empty/lightly loaded fuel economy. I was planning to install an overdrive transmission that would have brought the empty/lightly loaded mpg up to around 25 to 27 mpg (based on experience of a friend with a similar truck). Another friend of mine had the same truck but with the standard rear end and automatic tranny with 4wd. He got 23 to 25 highway and he drove a lot faster and harder than I do.


Towing my cargo trailer with the Dodge @ 70 mph I got 17 mpg, with the 5th wheel @ 70 mph 12 mpg and 14 mph @ 65 mph.


Highway mph... Chevy gets 16 mpg at 70 mph empty, 13 with the cargo trailer @ 65 mph, and 10 with the 5th wheel @ 60 mph.

The truck currently has only 8600 miles on it. Hopefully mpg will improve with the VA box and more miles.


Bottom line... for performance (mpg & towing) the old Dodge beat the new Chevy hands down... but my new truck beats the tar out of the Dodge for comfort and smoothness . This is one sweet ride... the wife loves it.:ro)