I'm looking at getting a new 3/4ton Chevy truck for work. I'll be keeping it for 2 years & will put 200,000 miles on it. I'll be putting 90% highway miles on the truck & won't be towing anything. Can anybody tell me what kind of mpg I can expect from the Duramax vs a gas engine? I'm trying to see if I'll save money on fuel with the diesel vs the extra cost of it. Thanks in advance for any info.

When I first made the switch from gas, I did the calculation and estimated the additional cost of the diesel would be paid for in approximaelty 100k miles. The largest factors are the cost of gas vs. diesel, and the anticipated MPG for both.

Alot of this will depend on the price of gas versus diesel. Here in WI, Diesel is cheaper. Other places I've lived, it's more expensive. What're the average prices in your area?

Alot of this will depend on the price of gas versus diesel. Here in WI, Diesel is cheaper. Other places I've lived, it's more expensive. What're the average prices in your area?

other factors to consider are cost of fuel filter's & additional volume of motor oil.

ron54 is correct. For my analysis I considered normal maintenance a wash, simply becuase I felt the increased oil volume would be offset by the extended oil change intervals, and the fuel filter changes would be offset my the lack of gas items such as spark plugs. Things like this can be argued either way.

If you go out andget this months issue of Diesel Power, it compares gas and diesel. They use Ford trucks, but it's still a good comparison. Also, if you do exhaust, intake, and a small chip you will prob gain about 4 mpg. It will pay off quicker that way.

Lately diesel has been 10 to 15 cents per gallon cheaper than unleaded. So what kind of mpg are you guys getting on the highway when unloaded?

I had a 2001 1500 Z71 and got around 12 to 13 mpg (on a good day) and was paying anywhere between $3.20 - $3.70 for gas here.
Traded it in and got my 07 Classic 2500HD and I'm getting 16 - 18 mpg and paying $2.90-ish for #2 Diesel..... If you ask me, go with the diesel....:driver:

It seems to be very dependant on the road conditions (type of road, grade, hills, etc.) and even more dependant on the speed I'm driving.

60 = ~20mpg
70 = ~18mpg
80 = ~16-17mpg

I'm getting much better mileage than my Z-71 XCab got and better than my wife's Yukon XL as well.

I run 90% highway and unloaded I average 16-17 mpg winter and 18-19 mpg summer. Truck is totally stock. Far better than a 6.0 gasser.

With the set up I have, big tires included, I can get 18mpg running about 70-75. I just added the FASS and am hoping for a litte better mileage.

I got about 21mpg on the highway with my 05 1500 with the 5.3 and an intake, exhaust and chip but all the people I'v talked to that have the 3/4 ton6.0 get 16 out of them at best. My 02 LB7 Duramax got about 20 if you kept it under 70, with my new 07 LMM I got 20 at 75 and its not even broken in yet. Around here the price of diesel is about 6 cents more a gallon which still makes the diesel cheaper than the 6.0 to run. The biggest thing to take into consideration is the $7000 premium you pay to buy the diesel in the first place. If you will not be towing the gas might be the better way to go. Hope this helps

I have had both. My diesel got around (average) 16-17 mpg. I haven't checked the gas burner yet, but from what I am hearing they get 12-13 Mpg. if you do the math

100,000 miles divided by 16.5 mpg equals 6060 gallons of diesel
100,000 miles divided by 12.5 mpg equals 8000 gallons of gas

most of the time here the prices are the same so 2.85 per gallon
FUEL
diesel= 17,271
gas = $22,800
diff of $5529

Add in the extra cost of fuel filters about 6 in 100k equals $210

I changed my oil every 5k in my diesel. I will change it every 4k in the gas.
So that is 20 oil changes in the diesel. @ $35 for the oil & filter = $700
"" ' " 25 gas @ $20 =500

throw in a gas filter or two $20


for a TOTAL difference of $5139 on 100k miles about the cost of the Diesel. And the diesel is much more fun to drive ;)
Now after 100K you have to figure in the plugs and wires etc.

I have a 6.0 gasser and i drive 95% highway in the summer. I am getting around 13-14 MPG. My buddy has a LBZ with the exact same specs as i do and hes getting around 19-21 on the highway. Here in california, as of now diesel is around 5-7 cents cheaper. Go with the duramax, i wish i did every day

Thanks for the great info. My company gets us a new vehicle every 2 years so I'm trying to figure if the $6000 cost of the diesel will save over 200,000 miles vs the gas engine.

Diesel is 30 to 50 cents cheaper where I'm located.....

I've had this discussion on a boat forum I'm on, and it's practically impossible to convince most non-diesel truck owners of the efficiency offsetting the additional initial expense.
First, not figuring in fuel mileage at all, you'll recoup a majority of the diesel $ upgrade at sale time, regardless of miles on the vehicle.
I get 6-7mpg better on avg in my LB7 than my 01 Ram 5.9 gasser.
Maint costs are something to consider, as most shops rape you for normal maint on a diesel. Doesn't seem to take me any longer to drain 10qts of oil than it does 5qts. If you do your own maint, the cost difference for maint is negligible over 100k-200k mi, only a few hundred $$.
Maybe the new gassers get alot better mileage, but I would think that's only in the 1/2 tons. A 2500HD 6.0 gasser isn't very fuel effiecient.
GO DIESEL

Thanks for the great info. My company gets us a new vehicle every 2 years so I'm trying to figure if the $6000 cost of the diesel will save over 200,000 miles vs the gas engine.
So if your company buys you a new vehicle do you have to pay the difference if you go with diesel or are you trying to convince them that diesel is more cost efficient? Sorry if I'm missing something, not trying to be a smart a** just trying to get some details to help you the best.
My opinion is if this is a company vehicle all you pay for is the gas/fuel I'd definently go with diesel. If you pay for gas/ fuel and all maintenance, depending on how often you do main., and if you do it yourself, I may consider gas. (Can't believe I wrote that). If you pay for nothing, diesel for sure.:)
Now assuming and all you want to determine is if you will save on a diesel over 2 years 200,000 miles compared to gas... well that's simple, all you or your company has to do is look at resale. You'll more then make up your $6000 difference when trying to sell or trade in a 2 year old diesel with 200,000 miles compared to a 2 year old gasser with 200,000 miles. Even if your company writes it off they'll still want to get the most back from the trucks as possible.
Just my opinion.

I'm 6,500 miles or so into my first GMC D/A. Even if I get rid of everything I use it to pull, I'll never be without a diesel again! It's fun to drive, comfortable, reasonably economical and almost never slows down on a hill.
jim

I would think diesel is the way to go. Not only is the gas mileage better unloaded, less frequent oil changes etc, but the biggest reason would be RESALE value. A gasser with 200k is pretty much looked at as needing a major overhaul so you will see far less on your resale value. A diesel with 200k on it will still sell for a decent return compared to a gasser. That alone would offset the original purchase difference upfront IMO.

Here is a private party resale value comparison from kelley blue book. Both trucks have the same options except the engine/tranny.
Gas (6.0) '06 w/ 200k - $23,365
Diesel (6.6) '06 w/ 200k - $30,810

There ya go, that alone screams DIESEL.

Here is a private party resale value comparison from kelley blue book. Both trucks have the same options except the engine/tranny.
Gas (6.0) '06 w/ 200k - $23,365
Diesel (6.6) '06 w/ 200k - $30,810

I don't know if this is correct. But you pay that difference in the beginning anyway.

If you are going to be towing a lot and carrying a heavy load for most of that 200K miles, get the diesel. Otherwise I'd get the gasser since the maintenance cost is less and the gas mileage isn't really that much worse.

However if the company is footing the bill %100 plus maintenance cost; get the diesel.

Purchase your d-max through GMC at a Cadillac dealer and chances are you get free oil changes (I do)! That'll save ya some $$$!

My diesel pulls my 12,500 lbs of toy hauler and toys. I know the new 6.0 gasser is rated for that weight; but like everything "I'll believe it when I see it". I'd challenge any 6.0 gasser up any of the grades around here in So CA and not only climb faster, easier, and with better gas mileage. There's no cost that can quantified a diesel's pulling abilities/advantages. Well, I guess there is: the $7,000+ upgrade charge to go from 6.0 gasser to diesel... well worth it in my book!!! :D

Here is a private party resale value comparison from kelley blue book. Both trucks have the same options except the engine/tranny.
Gas (6.0) '06 w/ 200k - $23,365
Diesel (6.6) '06 w/ 200k - $30,810

There ya go, that alone screams DIESEL.



If you compare two older vehicles, lets say an 02 gasser vs an 02 diesel that margin gets wider considerably.

From what ive read lbz's are hits or misses on milage (some 20 some 15 empty highway). W/the diesel and allison you get a 3.73 rear end and 6spd double overdrive to keep the revvs down on the highway. You ahve to do the math the diesels about an 7k premium so you have to take fuel prices in your area maintanance dont worry about a few more quarts of oil isnt a big deal. diesel highway miles id say you can run 7k mile on oil changes safely.
Resale on a 200k mile diesel wont be too bad, on a gasser much much less. To me extra cost of the diesel up front will made back on resale (most of it.

I had a 2001 3/4 4x4 with the 6.0. It ran great but, best i ever got was 14 mainly 13 in the summer. The 06 LBZ pretty much same truck equipment wise, I get 18-19 in the summer driving my regular day to work etc.
Now throw a wrench in the works, the new 6.0 has a 6 speed auto (Hydromatic) and 3.73 gearing instead of the 4 speed auto and 4.10's. Food for thought. Happy shopping. :D

I just turned 4200 miles and reached 20 mpg on my 2007 classic lbz. The mileage keeps getting better. Hope to maybe hit 21 or 22 later on.

My LBZ gets about 18 MPG on the highway unloaded at 70 MPH, my 2002 6.0 L configured otherwise similarly got about 13 MPG under the same conditions. The new 6.0 with a 6 speed trany may do a bit better though.

After driving a Diesel, I don't care what the difference is. I do not think I will buy a gasser again. Hoping GM will do that new diesel in the H2. Once it proves itself I plan to convince my wife that is her new SUV.:D

Well everyone has covered just about everything. My last pickup was 2004 2500HD 6.0, identical to my 06 classic duramax. I too did the comparisons, and "cost justification" and came up with the same 100k mile 'payback' mentioned earlier. The 04 6.0 was a great truck, and towed well, and average 12.2 mpg.
Regardless of all the math I did, and all the research I did I can honestly tell you there is only ONE reason I bought a DURAMAX...

I DROVE ONE!! that was it, I did not care about payback after that. My duramax would blow the doors off my 6 litre!! Not to mention the fact that it will also out tow the 6 litre.

Almost forgot, mileage on the DURAMAX - 20.1 mpg average over the last five tanks of fuel!!

I believe if you have your buisiness look at resale as mentioned by others it may offset the higher sticker price. Not sure what the depreciation is over two years on gas vs. diesel???

The company buys the truck & they give me a fuel card & a Valvoline fleet card to get oil changes + other maintenance. My boss is all about the bottom line so I think I can sell him with the fuel savings, resale value, etc.

What or how much weight are you hauling that you need a 2500 truck? That will tell if a gas or diesel motor will be best. My 2006 empty and 60mph will get around 20 mpg on highway runs with two or less stops per 100 miles. At 65 about 19 and at 70 about 18. I never got more than 13 mpg on the 2004 6.0 driving the same.

With a gasser and a 26 gal tank, you'll have to stop for fuel about every 350 miles ( 22 gals X 16 mpg.....my fuel light comes on at 22 gals used). With a diesel doing the same driving, you'll have to stop every 440 miles. The first thing I noticed when I moved out of my 1/2 ton gasser into the duramax was how SLOW the fuel gauge seem to move :D . If you're doing highway miles for work, the mileage may play a big role.

Other thing I have noticed with the diesel is consistently good fuel mileage. The gasser tended to vary easily.

The answer seems clear to me, given mileage and resale value. Also, if Biodiesel is available in your area, then you (and your company) can go green. Oh, and my wife likes the fact that diesel is bascially non volatile - meaning, if you get t-boned, you won't explode.

And of course, it's a joy to drive. If you need a 3/4 ton class truck for the job, then you are hauling stuff, otherwise the company would buy you a 1/2 ton. Half tons are too soft IMHO to carry much of anything around all the time. With the weight in the bed on those soft springs, the nose goes up and handling suffers. The 3/4 ton is a workhorse, yet is a comfortable driver.

GO DIESEL.

The diesel with still be worth something after 200,000k. A gasser will be ready for a transplant.

the diesel with still be worth something after 200,000k. A gasser will be ready for a transplant. x2

Don't forget to factor in future resale or trade value on Diesel -vs- gas engine, which (Gas)depreciates very rapidly with mileage.

At 200k you are just breaking in the duramax

I sure wish I had the same mileage as some of you guys. I can get 35mpg in my Duramax going downhill too. However, I don't get anywhere near the 20 some of you guys get out of a tank. Best I've done is 16 on a 900 mile trip to California. I get 14 around town and 11 towing on flat roads.(I drive very conservatively and don't have my foot in it.)

I bought my truck hoping to get better mileage than my old gasser ('96 1/2 ton 5.7l).

The LBZ is a lot stronger for towing but I'd like to have tried a 6.0liter before I bought my Diesel. People say the diesel will smoke the 6.0. I agree the diesel will set you back in the seat but I'd be willing to bet the 6.0 will take it off the line and at 50mph. Mine has such a huge lag it takes about 3 seconds after i hammer it down before it takes off. I think a gasser would get quite a jump.

To replace the fuel and air filters in my truck just cost me $100. $40 for the fuel filter and $60 for the air filter(NAPA). $150 to put the fuel filter in according to the dealer. I did it myself and it took all of 5 minutes. To do the same on a gasser would probably cost around $30.

Also, in the winter your going to pay .10-.20 more for diesel than premium gas because the cost of diesel goes up with heating oil. In the summer you'll pay .10 less than regular unleaded. However, for some reason the price of diesel varies greatly from station to station. My figures are best case scenarios.

Don't get me wrong, I love my truck for towing. I bought my '06 used(22,000 miles) and got a good deal and didnt pay the $7000 difference. If your going to do a lot of towing and will keep it for 200,000 miles you may recoupe the cost of the diesel. If you tow very little and aren't planning on putting high mileage on it before you trade it I don't think it's worth the initial investment.

What or how much weight are you hauling that you need a 2500 truck? That will tell if a gas or diesel motor will be best. My 2006 empty and 60mph will get around 20 mpg on highway runs with two or less stops per 100 miles. At 65 about 19 and at 70 about 18. I never got more than 13 mpg on the 2004 6.0 driving the same.

That is pretty darn close to the same numbers I am seeing with my LBZ and my 2002 truck with a 6.0. The only part that the gas truck beats the Duramax on is that it warms up a lot faster. The LBZ takes 5 to 10 miles to reach full operating temp, while the gas truck takes about 1 to 1.5 miles.

Averaging a shade under 18 MPG hand calc'd around town with mine (see sig), 21+ straight highway. 10k miles.

Well everyone has covered just about everything. My last pickup was 2004 2500HD 6.0, identical to my 06 classic duramax. I too did the comparisons, and "cost justification" and came up with the same 100k mile 'payback' mentioned earlier. The 04 6.0 was a great truck, and towed well, and average 12.2 mpg.
Regardless of all the math I did, and all the research I did I can honestly tell you there is only ONE reason I bought a DURAMAX...

I DROVE ONE!! that was it, I did not care about payback after that. My duramax would blow the doors off my 6 litre!! Not to mention the fact that it will also out tow the 6 litre.

Almost forgot, mileage on the DURAMAX - 20.1 mpg average over the last five tanks of fuel!!

I believe if you have your buisiness look at resale as mentioned by others it may offset the higher sticker price. Not sure what the depreciation is over two years on gas vs. diesel???


I agree I had an 04 silverado 2500 with the 6.0 in it. I got around 20L/100Km (11 MPG) running empty doing half highway and half in town. Now I just bought an 07 classic 2500HD with the same load (LT) LBZ and in the exact same conditions I'm getting 16MPG (and it's not broken in with 2600KM, Only had it for a month ;))

Having all those stats I love raw power and the 6.0L had that off the line it would take the diesel but by the next light The LBZ would take ya. Now for fun put a moderate load say 6000lb behind each truck and line them up... The LBZ will smoke the 6.0 hands down...

Now I did the same thing I went to the dealer sat in one and said to myself ... Ya looks the same as the old one a few more bell's and whistles no big deal... Then I started it and drove it down the street...... SOLD!!!!!!!!!!!!!! The sound of the turbo and the power and accell when that whistle sound kicks in is like a kick in the A$$. I recently had a car trailer with a full size truck on it and had to bring it to a location about 400KM away and I live in BC, Canada land of the mountains so ther were some hills.... When I did similar loads with the 6.0 it did go up better than my old 350 but you had to really floor it to keep it moving under the weight where with the diesel I just hold the accell moderately ..(under half throttle) and was flying up at 100KM just nicely with out forcing.

Best advice I can give.... GO DRIVE ONE.

I just turned 15K on my o6 LBZ. Took my first trip with it empty last week, 900 miles round trip. I got 21 mpg with the cruise set at 75 and using my right foot to navigate traffic in S. Chicago and Detroit. My 6.0 I had would have gotten around 12 on that trip and my 8.1 would have gotten about 10 on that trip. As others have said, if I sold my boat and camper, I would still drive a diesel!!!

You guys have been a great help. I don't NEED a diesel, but have one (personal truck, not a GM) with 250,000 miles and like being able to get the extra distance between fuel stops, and I have a 50 gallon transfer tank I'll put in the new truck which will enable me to go a lot further. This will be my first Duramax, so I'm looking foreward to seeing how I like it.

wadecool, you will enjoy the Duramax and will find out in a short period of time what you have been missing. I hope you enjoy your new truck.

My personal truck is an 01 Dodge CTD. I LOVE the Cummins, but am FED UP with Dodge & how they treat customers like s***. It seems like everything else but the Cummins motor has broken (on my 3rd nv4500 5spd). I have always told people, "I'm not a Dodge guy, I'm a Cummins guy". I like the looks of the Chevy, and I do believe Chevy will be a better overall truck, but I'd love for them to offer Cummins engines in their trucks.

Alot of this will depend on the price of gas versus diesel. Here in WI, Diesel is cheaper. Other places I've lived, it's more expensive. What're the average prices in your area?

Where are you buying your fuel? It is almost always more expensive over here by the Dells.

Diesel is about .10 to .15 cents cheaper per gallon in KY. Also, with the diesel work truck, I can occasionally put a little fuel in the wifes 06 VW Jetta TDI.

Where are you buying your fuel? It is almost always more expensive over here by the Dells.


It's almost always cheeper here (BC Canada) but it can go higher usually in winter due to heating oil.

I like the looks of the Chevy, and I do believe Chevy will be a better overall truck, but I'd love for them to offer Cummins engines in their trucks.

I doubt that will ever happen, but you never know these days. GM and Izusu split, Cummins will run out of contract soon, and seems that there are others splitting as well. So the market might be open.

The original post said you wouldn't be towing anything, so I have to ask, why do you need a 3/4 ton? Seems a 1/2 would suffice, and the 5.3L gasser would be cheaper to maintain, a much cheaper vehicle, and the mileage would be about the same. I have an 06 1500 Z71 Crew with a 3.73 rear, and get 18.5 mpg highway and about 16.5 - 17 in town.

The gasser might be cheaper to buy out the gate, but the diesel will hold value much better ofsetting some of that cost. Combine that with the fuel savings and the difference might be fairly minimal. Anyway, the DMax is a lot more fun to drive than the 5.3 and that has got to be worth something :)

I just got myself and 06 LBZ it has now 60,000 on it. I live in idaho and i flew to atlanta to get it and i drove it back. The truck has the edge chip in it and i was doing between 70 and 75mph for 2 days straight (day and night) and was still in the 20s for mileage. This is my first diesel, I havent even had it for a week and I cant help but wonder why i didnt get one years and years ago ......:D :D

I don't haul anything a 1/2ton couldn't handle, but with the 3/4ton I could put my 50gallon fuel tank in the bed & tap into the fuel line. Then I'd have the 26 gallon + 50 and be able to go pretty far between fuel stops. On Wednesdays I travel 550 miles, Thursdays I travel 450 miles. I plan to talk a dealer into a 24hour test drive soon to see how I like the Duramax.

better mileage, cheaper fuel... buy the diesel.
Don't drive it like you just stole it. Drive it like you normally would, and you will have no problems. Perform the maintenace yourself, trust no one to service your truck. Repeat: trust no one. Trust the people from this forum. They have been right every time. And I thank everyone.

Buy the DuraMax

My two cents.

Perform the maintenace yourself, trust no one to service your truck. Repeat: trust no one. Trust the people from this forum. They have been right every time. And I thank everyone.

Sadly, I have found that to be VERY true. Most people do not take pride in thier work, they just do a slop job and want your money for it. Unfortunately this leaves the few who do great work surrounded by crowd of hacks, and it leaves the consumer with the difficult task of sorting them out.

I run 75% small country roads, living in town of about 900 people. I get anywhere from 18-20. Totally stock 2004 LLY. I do some towing (Lawn mower trailer) thats about it though. Love the truck!!

I wish it was the same in California as it is in the rest of the country.

Right now, Diesel is on the magnitude of 20-30c more EXPENSIVE than 87 RUG...

The cheapest gas in Los Angeles (in Downey, where I live) is 2.77 and ranges between 2.77 and 2.85 for the most part.
The cheapest diesel I can find around me (in the same city), is 3.09 and ranges from 3.05 to 3.39, with the majority of stations around the 3.29 price-point.

Kinda Sucks now that we're on the opposite end of the spectrum and winter hasn't even hit yet.

Still even with higher diesel prices than gasoline, i won't drive a gasser...
Just will be more selective on my trips, it was actually cheaper to drive my girlfriend's Audi A4 (uses Premium) down to San Diego and back than to drive my truck (getting 22mpg on the hwy).

don't compare regular gas v diesel #2......compare it to supreme gas v diesel because there's only one grade in summer. there's no choice on it. there for to get the best in gas you have to purchace octane 90+ compare to #2 diesel the saving are alot better when you do this. for excemple my bmw gives my wife a 27 to 28 mpg on hwy, my truck does 19.5, the bmw runs like shit on regular so she has to buy supreme at 3.65 a gallon ,i'm buying diesel at 3.04 a gallon. you do the math!!!!! my truck is cheaper to run!!

don't compare regular gas v diesel #2......compare it to supreme gas v diesel because there's only one grade in summer. there's no choice on it. there for to get the best in gas you have to purchace octane 90+ compare to #2 diesel the saving are alot better when you do this. for excemple my bmw gives my wife a 27 to 28 mpg on hwy, my truck does 19.5, the bmw runs like shit on regular so she has to buy supreme at 3.65 a gallon ,i'm buying diesel at 3.04 a gallon. you do the math!!!!! my truck is cheaper to run!!

Lol... if only premium was 3.65 here... its 3.09... same prices i paid for Diesel last week.