mpg report after 4000 miles

Irish80 · September 17, 2019

Well I have just over 4000 miles on my 2020 3500 Duramax and I thought I would share my mpg for anyone interested. About half of those miles have been towing around 11,000 lbs or so. I'll put it in a list so it's a little easier to read. I'm using hot shot's secret edt so I'm not sure if that helps the numbers or not. What are you guys getting and what are your opinions on fuel additives?

•Empty driving to and from work(9 miles) and some city driving is around 17.5 mpg.

•highway empty is around 21 mpg(one 25 mile stretch according to the truck I got 25.1 mpg)

•towing 2860 lb flatbed trailer empty is around 16 mpg and as good as 18 mpg.

•loaded trailer on a lot of rolling hills is usually around 13 mpg.

gearheadesw · September 17, 2019

Damn thing gets the same mileage towing as my 6.0 gets empty, grrrrr.

SkidooSteve12 · September 18, 2019

14 hours ago, gearheadesw said:

Damn thing gets the same mileage towing as my 6.0 gets empty, grrrrr.

haha yeah, but it would take over 10 years to offset the additional cost of the Duramax vs Gas motor. Trust me, I tried to justify a diesel every way possible before I bought my new 6.6L Gasser.

gearheadesw · September 18, 2019

Well, $10,000 will buy a lot of gas.....

@SkidooSteve12, you have a new 2500? And you had some experience with the outgoing model? I really like the numbers posted for the new gasser in another thread, how do you like the new truck and gas engine? I have zero problems with the 6 speed transmission, but do you think it’s needed , or would the new 10 speed make any difference. Unless you’re towing real heavy, I can’t see the extra gears making much difference, I dunno.

KARNUT · September 18, 2019

Funny little story, I’m old cut me slack. I know the 6.0 is a beast and probably the new one is too. Back in 95 the dodge V-10 was hot. The Cummings was bulletproof then but diesel were painfully slow without mods. I ran the numbers looking for an excuse for the V-10. 300HP verses 165, TQ the same. More RPMs better down shifting on hills less speed loss. Ah, price difference equals 40K miles free fuel. The V-10 was like driving a hot rod empty. Pulling was less stress. I hit a hill down shift no speed loss. The dealer said it could handle whatever I dished out. The exhaust would get so hot it melted the undercoating. Out of town going to a demo show hauling my machine it happened. I noticed power loss. Pulling over to fuel up oil pressure drops. I kill it. Open the hood, the dip stick push out oil every where. I had just turned 40K miles. The dealer did cover it. They claim bad injector seal and lean out. There were 3 blown pistons though. The big advantage of diesel is power lower. If you’re pulling within limits and keep RPMs low gas can handle it. I believe high RPM downshifts killed the V-10 and bad tuning.

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SkidooSteve12 · September 18, 2019

13 minutes ago, gearheadesw said:

Well, $10,000 will buy a lot of gas.....

@SkidooSteve12, you have a new 2500? And you had some experience with the outgoing model? I really like the numbers posted for the new gasser in another thread, how do you like the new truck and gas engine? I have zero problems with the 6 speed transmission, but do you think it’s needed , or would the new 10 speed make any difference. Unless you’re towing real heavy, I can’t see the extra gears making much difference, I dunno.

@gearheadesw I just posted here because I agreed with another post on the mileage of a 2013 1500 5.3L

I have a little over 450 miles on my new 2500 6.6L and put most of those miles on the truck. It had 37 miles when I took it for a weekend test drive and put most of the miles on it before buying it with 177 miles. I came from a '13 1500 5.3L that I put 93K miles on from new. Before that I had a '05 1500HD with 6.0L and 3.73 gears that I put around 60,000 miles on if I remember right. I think the 6 speed fits just fine. I haven't hooked up any of my trailers yet, but I can feel the low end torque when taking off from a stop and can keep the RPM's down compared to my 5.3L. I don't expect to be towing very heavy loads very often, occasionally moving some tractors around and our travel trailer. A lot of my decision to go to a 3/4 ton was for pulling my new 7.5'X29' snowmobile trailer on winter roads. My old '13 1500 had enough power to pull it and got decent MPG, but it wasn't a very stable ride during a winter storm and it wasn't even fully loaded. The safety factor of pulling with the 2500 had me searching for a nice used 3/4 and I didn't even have a new 2020 HD on my radar haha. But it just worked out getting this truck off my dealer's lot for the price deal that fit. If the 2020 didn't have the new 6.6L I would have kept searching for a used 6.0L. I normally don't like being the guinea pig with new models but I took a leap of faith on this truck and really like it so far!

CRApex · September 18, 2019

1 hour ago, SkidooSteve12 said:

haha yeah, but it would take over 10 years to offset the additional cost of the Duramax vs Gas motor. Trust me, I tried to justify a diesel every way possible before I bought my new 6.6L Gasser.

It will certainly take longer to offset the Duramax cost, no disagreement there. I think most buy it for the towing experience though and understand there's a cost for that. You do get a good amount back on trade for the Duramax as well.

redwngr · September 18, 2019

Lets face it.

If it was just economics we'd only ever buy used trucks.

Pfc1 · September 19, 2019

I have owned 3 1500's before buying my 2018 2500 HD Duramax and I haven't seen any big difference at all between the gas mileage. Most of my driving is highway so that helps. I average about 22.5 consistently. Extremely nice when towing our camper, no down shifting, just cruising. So know we will see how my new 3500 HD Diesel dually runs with the higher gear, I'm guessing it should do a little better just because of the gearing.

Irish80 · September 19, 2019

I bought it because I'll be putting on 60,000 miles a year and a good chunk of that will be towing. It won't take me near 10 years to make up that difference since I was only getting 7-8 mpg with my 6.0, maybe 9 on a good day. all those miles are for work not play so the more money I save at the pump the more that goes in my pocket. I'll save approximately $4000 a year at current fuel prices, after 2.5 years it's all profit.

MrGraff · September 19, 2019

I've got just shy of 3000 miles on my 2020 Duramax, have not towed heavy yet still waiting on my hitch to come in. However have had several long trips and I am consistently seeing 19.5-20.5 and that's doing 75-80mph on Texas and New Mexico roads with random wind. Comparing this to my outgoing 2019 Duramax, I'm seeing around 2-3mpg better mileage overall on the highway. Currently calculating city mileage over a good amount of time before I report those numbers. I think the mileage is improved mostly due to the 10 speed transmission and new DEF usage characteristics.