Duramax towing MPG

[timswi]

I was planning on buying a DMAX for my next truck..If the EPA version is this bad, I'll stick with gas. The guys I know with the older ones were getting in the low to mid 20's on the highway. I don't know anyone with a new one.

 

[Diamondpilot]

You tow 5000# behind a S70? Thats a lot of weight for a 4000# car.

Aaron Z

In Europe things are different than here. But in all honesty many people tow 7,500# or more behind 1/2 tons that weigh 5,500# like me. I also tow 15,600# every weekend behind my 7,600# 1 ton SRW and many tow more than that.

Chris

 

[Diamondpilot]

I was planning on buying a DMAX for my next truck..If the EPA version is this bad, I'll stick with gas. The guys I know with the older ones were getting in the low to mid 20's on the highway. I don't know anyone with a new one.

Both my 05 and my neighbors 07 got right at 20, maybe 21 on a good day with our Dmax. I do not think that is common anymore. My friend has a 08 2500 4x4 and he gets about 16 at best.

Chris

 

[Dargo]

What I don't understand is how I can get 10.2 to 10.5 mpg (running the speed limit) with a 35,000 pound coach being powered by a Cat C9 http://ohe.cat.com/cda/files/448361/7/LEDT7015 -C9 Engine Brochure 8.9.07.pdf engine. It's not absolutely huge by any real measure, but it is a 9.3 liter engine that weighs about 1700 pounds. I do have the 6 speed Allison engine coupled to it and it only turns about 1500, or so, RPM at 70 mph. The part that gets me is that the aerodynamics are about as bad as you can get and I'm always towing at least a 4000 to 5000 pound vehicle behind me.

If they can get that MPG with something that big and heavy with no aerodynamics, why do I only get about 1 mpg better with my F350 when pulling around 16,000 pounds? It's only a 6.0 liter engine and it has a lot better aerodynamics and weighs a huge amount less. Man am I confused. Maybe I ought to look for one of those big RV coaches that has had the body destroyed on it but still has a good C9 engine and Allison drive train. It would have a heck of a lot more power, a B50 life expectancy of 750,000 miles and get better MPG with a little aerodynamics. Heck, it might be neat having a pickup with a 30' long bed.

 

[timswi]

Both my 05 and my neighbors 07 got right at 20, maybe 21 on a good day with our Dmax. I do not think that is common anymore. My friend has a 08 2500 4x4 and he gets about 16 at best.

Chris

I get 17 MPG with my 04 GMC 5.3 w/3:37's ...And I beat this thing hard. 80+ MPH on the interstate and running the other half of my 60 mile round trip on windy country roads....What is the EPA doing here? Good grief, my '89 3/4 ton 6.2 diesel Suburban did better than the new diesels. No win I see.

 

[aczlan]

In Europe things are different than here. But in all honesty many people tow 7,500# or more behind 1/2 tons that weigh 5,500# like me. I also tow 15,600# every weekend behind my 7,600# 1 ton SRW and many tow more than that.

Apparently, I was being generous with the vehicle weight (at least for a US spec '98 S70), it is listed has having a curb weight of 1454kg (3198.8 pounds) and a max GVW of 1900kg (4180 pounds). Dad had one of those with a Turbo in it and it squatted with a 3500# equipment trailer behind it. IIRC, the US spec ones aren't rated to tow more than 3500# (1500 wo/brakes).

I suppose though, that a 5000# dual axle trailer behind an S70 wouldn't be too bad as long as it had decent brakes on both axles and the load was properly balanced.

Aaron Z

 

[brain55]

10-12 mpg towing 17-18 unloaded would be awesome. Beats the heck out of 5 mpg towing and 9ish unloaded.

87 octane unleaded around the corner from my house is $3.13/gallon
diesel is $3.25/gallon

Theorectically my fuel bill could go from $1000/month to $520/month.
I realize the diesel is a little more to maintain but a truck with 200,000 miles on it is not exactly cheap to maintain either.

I know my wife will exercise her veto power, and I agree. Even though on paper it would probably only be a couple of hundred dollars more a month for a new truck, I will wait until next year. It will give us a chance to pay down some other bills before I pop for a $55,000 truck.

Brian

 

[Dano5509]

I have a 2005 Silverado 3500 SRW Long Bed Crew Duramax/Allison. It has an AFE Stage 2 air intake/filter and pulls 18mpg with the 3.73 gearing and an empty bed. Pulling our Jayco Eagle 5th wheel at 10k lbs it goes down to 12.

It does not have the DPF and I am going to put a 4" MBRP downpipe-back exhaust on it soon and maybe a Max Energy tuner. I don't want to wind the Duramax up too hard and will try the tuner on the 1 or 2 setting to see how much of an improvement I get with the cold air intake/exhaust/tuner.

Xtreme Diesel Performance has some interesting "kits" available for the DPF equipped trucks...

 

[Ford tractor]

Every year the duramax has gotten more HP and less mpg. This year's version has tons of power and the lowest economy yet. I drive an older LB7 version and get 18-20 empty and 12-14 towing 10k (tractor).

Given the $10,000 premium for the diesel, I'd just get the gas engine in a new truck. The new anti pollution solution scares me. I've heard DPF's out of warranty will be $1000-1200. Who knows what the urea systems will do. Plus the new gas engines are much more economical and powerful than the old ones. There is no longer a clear justification for diesel unless you run 40-60k a year loaded.

 

[Renze]

You tow 5000# behind a S70? Thats a lot of weight for a 4000# car.

Mine is a first generation S70 (basically the facelifted 850) which weighs 3200 pounds, and i've towed 6 silage bales with it, about 7000 pounds loaded. At that weight, wheelbase of my trailer, and height of center of gravity, its better to take the small roads and not exceed 60km/h because its clearly way beyond a point where i would let others drive.

The time i towed 5000 pounds was a long wheelbase 20ft tandem, which is more stable than my own 12ft tandem. We took a tractor home with the cruise control at 115 km/h, so it could run in 5th gear at the engines "sweet spot" , max torque at 2200rpm.
I'm thinking of installing HD rear springs of a V70 estate to increase the stability, to be able to tow bigger tractors every now and then, and to increase the hitch load from 75 to 150kg, when towing 5k lbs.

I suppose though, that a 5000# dual axle trailer behind an S70 wouldn't be too bad as long as it had decent brakes on both axles and the load was properly balanced.

With the tractor i stopped twice in the first 2 miles to roll the tractor back and forth to reach optimum weight distribution before i hit the highway. The trailer was a 3.5 ton (7700 pounds) with two 1800kg axles with surge brakes. When properly maintained (the brake bowdens need replacing at least every 5 years, or 2 in commercial use) the trailer will smoke its tires when you hit the brakes hard.
By law, in Europe everything has a brake force which equals 45 to 55% of the weight on the axle. at my former employer we allways liked to stay above 50% because bowdens start to brush off after a year or two and the friction in the cable reduces the brake force.