Comparing 3/4 Ton Trucks: Fuel Economy

[Vic Harder]

My 2004 Dodge 1500 5.7 quad regular bed gas gets 11mpg (highway) with Camper. Without camper, about 14 (highway).

- so my 2500HD 8.1 is getting better mpg than your 1500 5.7 was? wow

 

[Ace!]

As some of us have stated previously, sometimes the bigger engine is able to work less (lower RPM) due to the additional hp/torque, so you see better mileage in a larger engine, especially as the load increases. Big gas engines are not the gas-hog (over a smaller engine) you might think, depending on the workload.

 

[JaSAn]

I just got back from a 3 week trip to the Upper Peninsula of Michigan:

• 2580 miles, 182.2 gallons = 14.2 MPG.

Observations:

• Got somewhere ~ 14.6 driving 50/55 MPH and slowing down to 25/30 for towns.
• Got ~ 9 - 12 MPG (OBC reported) when driving 10 - 25 MPH on gravel and dirt back roads.
• OBC reported 16.8 MPG on one hour of uninterrupted driving with cruise control set at ~56 MPH. Traveling East with gently rolling hills, WSW wind at ~ 5 - 10 MPH.

2012 Ram 2500, 5.7L, Auto, Grandby, GVW just under 8000 lbs.

jim

 

[ntsqd]

With our Cummins 6BT I really notice the mpg's drop when I drive faster than 1750 RPM, be that in OD or Direct. It is more noticeable in OD because of the air resistance due to the higher vehicle speed, but it happens regardless.

With a gas engine I've always tried to find where it makes its peak torque and drive a little slower than that. With a gas engine (not sure if also true with a diesel or not) peak torque always happens at the RPM where its best Brake Specific Fuel Consumption (BSFC) occurs. BSFC is simply how much fuel for how much power and the lower the number the more efficient the engine is operating. Seems to me that cruising at that engine speed is the most ideal, if possible.

 

[clikrf8]

When we drove to Colorado to pick up our Hallmark, we drove the dreaded interstates almost the entire way including the blustery one across Windy Wyoming. MPG was around 14+ or - unloaded.

2008 Ford F250 6.4 liter SuperDuty diesel, long bed, extended cab. He uses the Tow-haul feature a lot.

With our fully loaded camper/truck with fuel, water, 2 people and 2 big dogs, we now average from 9.7 up to 12.4 depending on the amount of passes and speed. We usually travel blue highways and/or USFS/BLM roads. Never above 60-65 mph on the highways and much less on the gravel roads. We also stop a lot to look at historical markers. Last trip was full of passes and we were often at 5,000 or 6,000 feet before ascending a pass of 8,000+.

Hubby is discussing putting in some module after our 5 year extended warranty is up next August. More research needed.

 

[Vic Harder]

Hubby is discussing putting in some module after our 5 year extended warranty is up next August. More research needed.

You will want to check out Idaho Rob - diesel tuning expert. He lives for duramax' trucks but tunes others as well

http://www.dieselplace.com/forum/3-power-performance-tuning/146-third-generation-duramax-electronics-tuners/561986-idaho-rob-tunes.html

 

[clikrf8]

Thank-you Vic.

 

[dharte]

In my 2005 F250 4x4 6.0 I get 13mpg average on trips carrying my FWC Hawk. I don't go out of my way to get better mileage-on the interstates, I will go with the flow of traffic, even if it's 70-80mph. My truck came with a slide in camper certification, and the weight of the camper is not really noticeable, except on really bumpy roads. Without the camper I used to get up to 16mpg on trips. What makes a huge difference is wind-a head wind kills the mpg, and I'm looking into ways to make the rig more aerodynamic.

 

[RisingSun]

Also tire pressure is something to think about. Recently I reduced my tire pressure from 70 to 55. MPG(city) dropped from 16 to 14.5.

 

[Vic Harder]

What makes a huge difference is wind-a head wind kills the mpg, and I'm looking into ways to make the rig more aerodynamic.

I've read here somewhere that the yakima style fairings reduce wind noise and can add 1 mpg on average. That would be worth it to me!

 

[Advmoto18]

2016 F-350 6.7L
~14 MPG around town.
>17 MPG on limited access highways at 65-70 MPH
1100# Hawk (loaded with gear) in the bed

My fuel economy is adversely affected more by B15 and significantly with B20 fuels than anything else.

Fairing may help, but as the aerospace industry has documented for the trucking industry, the aerodynamics aft of the vessel are as important as the front. Turbulent air aft of your rig is going to cause nearly as much drag as the front. If you are traveling heavily used roads (lots of traffic), fairings will have minimal influence on inproved fuel economy as the air you approach is already turbulent from traffic.

 

[sourdough]

If you are hauling/towing a gross amount of weight, go diesel. If I was still hauling a FWC popup, I’d have a 3/4T gas truck.
My Tundra 4.7(gas) 4x4 with Hawk shell was always very near it’s 6,200 lbs. GVW or a little over. It averaged 15/16 mpg at 60/65mph
Now I have a Ram 3500HD(diesel) 4x4 dually with a Tiger CX coach. Loaded it weighs in a 11,200 lbs., still a full 1,000 lbs. under it’s GVW and averages 13.5/14.5 mpg @ 60/65 MPH. It only has 2,800 total miles so is still breaking in and MPG will improve I’m told. If I put lockout hubs on the front axle, guys on the diesel forums say another 1 to 1.5 mpg gain is possible. Close to the same MPG IMO but a big cost difference to carry the extra 5,000 lbs. that isn’t even possible with 1/2/3/4 T trucks
BTW, Newer diesel trucks with less smog than my 2012 use DEF and get better MPG. Older pre-smog diesels get better also.

 

[Vic Harder]

Adding to this thread...

Having shown my truck and camper to a nice couple from Holland yesterday, I got to thinking (again) about what my next truck/camper combo would be. I had been thinking of a Colorado/Canyon but discovered to my dismay that their version of a long-bed isn't - it is only 74" (6 feet 2"). Used trucks access cab (suicide rear doors) with an 8' bed are rare around here, so I started digging, looking at stuff like turning circle, payload and MPG, and I found some cool stuff!

First, using the handy google search phrase - site:www.wanderthewest.com mpg I found these previous threads:

http://www.wanderthewest.com/forum/topic/6082-an-experiment-how-much-does-the-camper-affect-mileage/

http://www.wanderthewest.com/forum/topic/12966-comparing-34-ton-trucks-fuel-economy/

http://www.wanderthewest.com/forum/topic/3979-what-is-your-mpg-with-fwc/

http://www.wanderthewest.com/forum/topic/1194-vehicle-type-and-fuel-mileage/

http://www.wanderthewest.com/forum/topic/12397-mpg-report/

http://www.wanderthewest.com/forum/topic/2742-expected-gas-mileage/

http://www.wanderthewest.com/forum/topic/9160-1st-gen-tundraeagle-mpg/

http://www.wanderthewest.com/forum/topic/1072-gained-2-mpg/

http://www.wanderthewest.com/forum/topic/10593-anyone-using-ram-ecodiesel/

http://www.wanderthewest.com/forum/topic/10836-cummins-67l-diesel-vs-gas-64l-hemi-v8/

Further, I note that there is very little consistency in the threads above about loads, speeds driven, wind direction, elevation changes, how aggressively we drive, you name it.

Plus I love my 2002 GMC 2500HD with the 8.1L (496ci) v8 and Alison transmission... It handles the load of the Hawk very well. Well enough that I can still drive speed limit everywhere, and even (what others might find aggressively) up hills or in the corners do I slow down. And I get 11.1 mpg (US) average.

I used to think I would get much better with a newer truck, or with a diesel. And even if I did, I decided a while back that even with a significant uplift in MPG, the cost of fuel vs the cost of the uplift to a newer truck, it just isn't worth it to upgrade. BUT, my truck is a short 6.5" bed, and I want a long bed truck. So an change is in my future regardless.

That upgrade will be a 3/4 or 1 ton truck, as I have no interest in running overloaded in a 1/2 ton (maybe an aluminum Ford F-150 though). Finding MPG info for 3/4 ton trucks is tough, as the EPA doesn't measure work trucks. Then I found Fuely:

http://www.fuelly.com/car/chevrolet/silverado_2500_hd?engineconfig_id=64&bodytype_id=11&submodel_id=
This is my truck, and I feel like these numbers are very real compared to mine.

Then there are these guys who do real world testing:

https://www.tfltruck.com/2017/09/heavy-duty-pickup-truck-towing-fuel-economy-trailering/

https://www.sdtrucksprings.com/best-mpg-while-towing-with-half-ton-pickup-f150-silverad-ram-1500

https://www.consumerreports.org/pickup-trucks/heavy-duty-pickup-truck-fuel-economy/

https://www.tfltruck.com/2018/03/top-10-most-efficient-trucks-towing-a-7000-lbs-trailer-on-a-100-mile-highway-loop/

Testing rigorously at 70 MPH and a 22K trailer, they are getting 6.5 to 8.6 MPG with the big diesels and gas V8's.

So I discovered that 11 mpg is actually really good, especially since these guys are doing 70 mph, and I get 11 ish at 80 mph. Mind you, that's with a camper on the back, not a 22K pound trailer. From what I can glean from the posts above, a trailer impacts MPG about 50%, and a FWC about 20%. In my case, the load seems to matter less, with less than a 10% difference between loaded and unloaded.

I also see from TFL Truck that diesels do NOT get better MPG than gas engines when fully loaded and working hard
https://www.tfltruck.com/2018-gold-hitch-best-towing-off-road-trucks/

Hope this helps others make a decision, and I would love "advice" on a 3/4" access cab long bed truck!

Vic

 

[klahanie]

and I would love "advice" on a 3/4" access cab long bed truck!

Beware of what you wish for !

my .02, two things...

1) skip the 3/4 and buy a 1 ton. I really don't get the 3/4 ton thing if buying for hauling. Yes, selection and availability could be a reason but if buying new I'd just factory order, not like I couldn't wait to spend 60K

2) buy what you want/like. It's your money. You're gonna drive it.

I looked at the fuely site for my truck. The very small sample of 6 reports about what I was getting... before changes... And for us that was average for long trips including gravel and always heavy but no city. So based on that I'd agree the site numbers are pretty real or. Usually tho there seem to be so many variables or the distances so short the mpg numbers posted in some enthusiast threads are hard to match.

As for gas same as diesel - I don't see the article - but IDK, that flies in the face of 20% more energy in diesel or whatever it is.

Also, I'll mention, in almost 9 years of ownership we have maybe once fueled up at a station where diesel cost more than gasoline (this in Canada). All the "is it worth it" threads I've read say otherwise (prob USA) but that has not been our reality.

There are other considerations with the gas vs diesel. Similarly there are other considerations with a truck purchase than fuel consumption.

Comparisons come down to what is important to you.

 

[Vic Harder]

Beware of what you wish for !

my .02, two things...

1) skip the 3/4 and buy a 1 ton. I really don't get the 3/4 ton thing if buying for hauling. Yes, selection and availability could be a reason but if buying new I'd just factory order, not like I couldn't wait to spend 60K

2) buy what you want/like. It's your money. You're gonna drive it.

I looked at the fuely site for my truck. The very small sample of 6 reports about what I was getting... before changes... And for us that was average for long trips including gravel and always heavy but no city. So based on that I'd agree the site numbers are pretty real or. Usually tho there seem to be so many variables or the distances so short the mpg numbers posted in some enthusiast threads are hard to match.

As for gas same as diesel - I don't see the article - but IDK, that flies in the face of 20% more energy in diesel or whatever it is.

Also, I'll mention, in almost 9 years of ownership we have maybe once fueled up at a station where diesel cost more than gasoline (this in Canada). All the "is it worth it" threads I've read say otherwise (prob USA) but that has not been our reality.

There are other considerations with the gas vs diesel. Similarly there are other considerations with a truck purchase than fuel consumption.

Comparisons come down to what is important to you.

Thanks... your opinion is one that I have value before and still do!!!

 

[smlobx]

Vic I will respectfully disagree with your assertion that heavily loaded gas trucks get as good mileage as diesels.

I have a small fleet of trucks and use them for a variety of jobs with my construction business. My 35+ years of experience has shown me that diesels get better mileage by a signinficant amount.

My F-350 SRW long bed averages 15.4 mpg and about 15.0 - 15.1 with my Hallmark camper on it. With the camper loaded I'm at about 10,800#'s.
Most of my co-owners who have gas 3/4 or 1 ton trucks are in the 10-12mpg range.

I am getting ready to upsize my tires and fully expect that to have a negative influence on our mileage.

 

[Vic Harder]

good feedback! i was summarizing what i read in those articles, and in there it seemed to say that when towing heavy loads, all big trucks suck fuel. your evidence says otherwise!

 

[klahanie]

Had to look twice but I saw the diesels tested with a 22,800 gooseneck and the gas with a 12,500 conventional trailer. Which is prob fair for real world scenario but not apples to apples.

I like to think going diesel vs gas gave us about 10% better fuel economy at about 10% cheaper fuel per liter. Call it 20%. That said I'd prob not buy another diesel but the Mrs would - go figure.

Incidentally we were averaging ~ 11 mpg with an intact V8 diesel, same as Vic's big block gas. So take your pick !

 

[Advmoto18]

Eddie...your thoughts and MPG observations are the same as mine. Albeit, I have the 156" wheel base F-350.

Along the SC coast, pure diesel (not sure what you call diesel without corn) is readily available. I often see 17-19MPG running on a tank of SC diesel fuel.

I've also witnessed 10.5 MPG after filling up with B20 diesel in Oklahoma. And OK diesel cost more than SC diesel by about .25 a gallon!

I've owned several F-150 gas trucks and never saw the MPG I've seen in my diesel Super Duties.

But like the old Shell Answer Man advise of the 70s, it might be my driving style.

While not a point of discussion, when hauling campers, the huge advantage of the diesel is available torque. With a lot more available torque, diesel trucks usually have taller gearing which results in lower cruise RPMs and generally higher MPG compared to gas trucks. But, a heavy foot on the accelerator will quickly negate any MPG advantage.

 

[Ace!]

The towing article with the gooseneck and conventional trailers wasn't a gas vs diesel article is was a brand vs brand artilce, a gas vs gas and diesel vs diesel article.

Torque at the rear wheels is a function of gearing. Published numbers are at the flywheel. So, if a truck is equiped with 3.31 gears and another is equipped with 4.30 they may have the same rear wheel torque numbers, or not be that different if you're only considering the flywheel torque number. Another way of saying that is a gas truck with 450 lb-ft of torque at the flywheel may have similar torque at the rear wheels as a diesel with almost 600 lb-ft of torque at the flywheel, depending on gearing. Diesel trucks usually have higher gearing than gas, and gas trucks have lower gearing, which works well because it puts both engines in their peak hp/torque ranges more of the time. It's not always the same, and there are so many variations between transmission and gear ratios that the difference may be negligible, or it may be significant depending on how you optioned your truck. The take-away, in my opinion though, is there isn't a hard-fast rule.

Sometimes gas trucks get better mileage, especially the turbo trucks (i.e., Eco-boost) and especially when unloaded. The diesel trucks can get better mileage than gas trucks, especially in the mountains and heavily loaded. Fuel prices vary by region (diesel is often higher than gas where I live), rear wheel torque varies (between models and options), what someone is going to haul and how often varies. You may need a slide-rule or an IBM super-computer to figure it all out.