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EcoDiesel vs HEMI towing MPG

Rau

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Hello everyone,

I apologize if this question was already discussed, I just didn't find it in this forum.

My question is how much mileage changes when towing the same load with HEMI vs ED with 3.21 and with 3.92 axle ration truck. I know it all depends on a driving style and a terrain, but were there any tests done by any truck owners or car critics to have an idea.

The reason for my question is I sold 2019 Laramie 1500 and will be back in market most likely in Nov or Dec. I and my wife really loved our camping trip to Colorado and thinking to buy a trailer to do more camping in this beautiful country. My previous truck didn't have a trailer break, had 3.21 axle ratio and was missing a few features I liked on RAMs. If we buy a truck I wanted to have an understanding on towing abilities with ED vs HEMI. If towing MPG on ED is considerably better than HEMI I would love to have long distances between gas stations.

Any information is appreciated. Laramie was my first truck ever, I owned it for 2 years and both I and my wife loved it. So I am newbie in truck and have 0 experience in towing trailers.
 

michaelf2780

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I have been looking at trucks for last few weeks to try to determine what I need. Here is a little what I have found and hopefully people can add to it as I am still confused myself and have questions. lol.

Gear Ratio will make a difference in max towing by a decent amount while lowing the MPG. Im not sure if I can link something here so wont but Edmends has an article with a few people commenting on it that most people will typically see 1-2 MPG difference with higher gear ratios. So for example the 1500 ED 4x4 with an estimated 21/29 MPG will have around 7800 lb towing with the normal 3.21 Gear Ratio but with the 3.92 it will have around 9700 lb towing with a lowed MPG of 19/27.

Here is one major problem with the above information though. Max towing is important but the trucks Payload is just as important and which can cause the most problems for people trying to tow with a Ram 1500. The average payload limit is only around 1750 lbs for the above example and the gear ratio does not improve that according to the Ram site. 1750 lb payload is not a lot and will be what limits what type a trailer someone can safely tow.

Payload is a tricky number as it all depends on your truck and its weight limits. But lets assume it is 1750 lb. A good rule of thumb is 10% of trailers weight will be on the hitch(tongue) for a normal travel trailer (a 5th wheel will be much heavier on the truck itself). This means with a 7800 lb trailer you are looking at 780 lb weight on the truck so you are now left with around 1000 payload. Subtract the people in the truck and anything they happen to add and it is reduced further. The more features you add the less payload you will have and the more dangerous it is for yourself and others, not to mention the wear and tear on the truck. People should go get there setups weighed to determine actual safe values.

There are also a lot of other factors that I am still reading about about elevation, wind, and shifting weights that will affect all the numbers.

I will still be buying a Ram 1500 ED 4x4 and pull a travel trailer but even if the 3.92 gear ratio is 9700 lb towing capably I wont be able to buy a travel trailer that can take advantage of that because the payload will not allow it because I want things like a moonroof and underseat storage. I will be limiting myself to 5500 lb light weight fiberglass trailers and even then when I am pulling I am going to have to reduce my normal payload to make it safe. That is if I can find the information to see if it can even work at all as I know moonroofs are heavy.
 
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Rau

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I am still learning myself, but I agree that payload is a first limiting factor than towing capacity so I am most likely not getting 3.92 axle ratio. The main question that remains open for me is ED vs HEMI as I do not know how they perform when you pull a trailer. I guess the safest option is to buy a HEMI as it is a proven engine. I personally drove one for two years and enjoyed it. Towing consumption rate is another thing I am really interested to know. I am kind a bit concerned with the numbers 9-10 MPG I heard for HEMI.
 

michaelf2780

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There are some Youtube videos that mention MPG and real world test. The test I saw was seeing the Diesel getting almost 35-50% better MPG than the Gas V8 when towing. So I am using 10 MPG for the V8 and the 14 MPG for the Diesel. If I drive to Vegas that would be 3000 miles round trip. That is 300 gallons for the V8 and only 215 gallons for the Diesel which means I need to refill less. Diesel does cost more but there are ways to help offset this increase.

Diesels do have its pros and cons, but the V8 proven engine is nice to have for peace of mind. I just drive enough and plan on getting a Extended Warranty that it makes sense for a Diesel.

(The 10 and 14 numbers above are just averages iv seen from youtube and other sources).
 
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AZHUND

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I'm not seeing any statements on what size trailer you are looking at. I have a small one (<2k gross - see my avatar) and got 14 mpg (compared to the 17 mpg mixed I have seen so far when not towing) with the 5.7L on my first trip using the new truck to pull it. In comparison, my Wrangler would probably get ~16 towing the trailer on same route and my old Taco would be ~15 or so. So I was happy and if you are planning on long road trips I would encourage looking at the smaller options out there (frontal area is really important) as they might meet your needs and then still get decent MPGs.
 
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2wd

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In my experience with the 5.7, when towing maximum capacity with bad aerodynamics (travel trailer 7-8k weight range) the Hemi will get 9-11 MPG.

TFL got 12.4mpg with the ecodiesel on their flat ground towing.

From purely a dollars and cents perspective, the ecodiesel is worth it if you're towing quite often, over long distances.
 
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dougf

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I picked up my 2020 Laramie 1500, 3.0L Ecodiesel, 3.21 on July 2. First trip, highway mileage was 30.1 mpg (at the pump), 427 mile trip avg 65mph. Next fill-up, city miles was 21.1 mpg. My first experience towing, 24ft Nash 22h (dry weight 4100, ~5500 for this trip, tongue weight 725lb - actual). At the CAT Scales, Steer axle - 3340, Drive axle 3820, Trailer axle 4520, total axle 11680. Door sticker shows 1385 payload. Vin lookup shows 8085 max tow. Based on this, I was close to my payload limit. MPG for 225 miles trip was 12.8. Second towing trip, 357 miles - avg 65mph from Pocatello Id to Riverton Wy, 13.5 (at the pump). Next leg was 11.54 mpg (either steady or strong headwinds.) Next leg 279 miles, hilly, some headwinds 12.83. Return trip from Nebraska on I80 (65-70mph most of the time) with some steady medium to strong headwinds, 12.17mpg (185 miles), 10.98 mpg (242 miles steady headwinds), 10.01 mpg (198 miles - STRONG headwinds). Last two fill-ups this month (not towing), 25.53 mpg (mixture 50/50 city, hwy - 304 miles). Trip to Dubois WY and back, mostly 65mph - 525 miles - 29.31 mpg.

I have found that towing with a 3.21 3.0L Ecodiesel drops the MPG drastically. I also found that DEF consumption also increases A LOT. The towing is as much as I will do this year and compares to how much I expect to do every year. City and HWY mpg when NOT towing is better than I had hoped for and when towing, mpg is mildly disappointing, but the truck handled the load just fine, even through the mountain passes. The MPG was every bit as good if not better than I was getting on my 2009 5.7 Hemi when towing. Overall, I'm pleased with the truck. No issues AT ALL so far, and since towing will play only a minor role in my use of the truck, I am happy with the purchase.
 
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WXman

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When I tow, I'm carrying 2-3 people in the truck, an ATV in the bed, an enclosed trailer on the hitch, and a 2,000 lb. UTV in the trailer plus camping gear. So I'm probably at 5,000 lbs. total load. I see a hand calculated 14 MPG on average like this.

When running 60/40 split of city/highway unloaded, I'm at 21 MPG.

This is with the mods in my signature. Also, the dash display is always optimistic so don't rely on it. For some reason it's not accurate in the diesel like it is on the gas trucks.

On all my prior Ram, Ford, and GM gas V8 trucks, I'd see 9-11 towing like this and 13-16 running unloaded. So, the diesel does provide better MPG....but diesel fuel also costs more, so...
 
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jdefoe0424

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Another data point for the HEMI, I have a 32' trailer 5,600 dry, 7,700 GVWR.(Haven't scaled it yet....)
I've been on several long trips and driving 65-70, without a windbreak I got as low as 8-9 MPG(gets even worse with a headwind of course). Drafting a semi I could get up to 10, maybe a little more if the wind was in our favor.
If you didn't drive highway and kept it at 55 I bet 10+ would be attainable with the hemi pretty easily, I hope to find this out at some point as highway towing is boring and not the point of owning a trailer. We're already trying to find the best route to cut down on some tolls with our trips from IL to NY.

I considered waiting for the ED, but my 9 mile commute would be hard on it and we didn't want to wait to purchase.
 
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silver billet

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Gear Ratio will make a difference in max towing by a decent amount while lowing the MPG.

Unless what you're towing is light enough that the 3.21 can tow it in 8th, there will be no difference in highway MPG between 3.21 and 3.92. The fuel savings from 3.21 kicks in only when the 3.21 can utilize 8th gear; otherwise if the 3.21 is in 7th or lower, it's game over and both transmissions will have very very close gear ratios, so RPMs will be almost identical at the same MPH.
 

Rau

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Another data point for the HEMI, I have a 32' trailer 5,600 dry, 7,700 GVWR.(Haven't scaled it yet....)
I've been on several long trips and driving 65-70, without a windbreak I got as low as 8-9 MPG(gets even worse with a headwind of course). Drafting a semi I could get up to 10, maybe a little more if the wind was in our favor.
If you didn't drive highway and kept it at 55 I bet 10+ would be attainable with the hemi pretty easily, I hope to find this out at some point as highway towing is boring and not the point of owning a trailer. We're already trying to find the best route to cut down on some tolls with our trips from IL to NY.

I considered waiting for the ED, but my 9 mile commute would be hard on it and we didn't want to wait to purchase.

One of the reasons I sold my truck was I am working from home for the last 6 months and probably stay in home office for another 3-6 month. However, if we are back to normal life my commute is going to be about 25 miles (40 min average drive time).
 

Rammit

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I know two people with the eco diesel. They get about 17 mpg towing a car trailer even with some hills (Mi to Las Vegas and West Virginia to Ohio). One was an enclosed trailer the other was an open trailer. By comparison my Hemi gets about 11-12 mpg towing an open car hauler and 9-10 towing a 22’ enclosed car trailer.
 
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Dragonmaster13

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I'm currently towing my 2014 Dutchmen 268BHS (33' tip to tail) with a 2012 Hemi Crew 4x4 and the old 6 speed trans. Dry weight is 6873, loaded scaled is 74XXlbs varying by about 100lbs depending on length of trip. I live next to to real rockies in Canada and tow some gnarly hills. Average doing 60MPH/100kph is between 6.5 and 8mpg depending on wind. Best ever towing was 9MPG on a trip with a tail wind, all hand calculated. Truck stays in 4th (1:1 gear on the 6 speed) at 2500-300rpms and will occasionally shift to 5th on downhills only. My sister hooked up to the trailer with her newer 8 speed and got 8.5mpg on the same trip I did at 7mpg, same RPM's. Long story, but if you plan tow I'd go ED all the way for the torque and lower RPM's and only with 3.92's, no 3.21.
 

Dragonmaster13

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I'm currently towing my 2014 Dutchmen 268BHS (33' tip to tail) with a 2012 Hemi Crew 4x4 and the old 6 speed trans. Dry weight is 6873, loaded scaled is 74XXlbs varying by about 100lbs depending on length of trip. I live next to to real rockies in Canada and tow some gnarly hills. Average doing 60MPH/100kph is between 6.5 and 8mpg depending on wind. Best ever towing was 9MPG on a trip with a tail wind, all hand calculated. Truck stays in 4th (1:1 gear on the 6 speed) at 2500-300rpms and will occasionally shift to 5th on downhills only. My sister hooked up to the trailer with her newer 8 speed and got 8.5mpg on the same trip I did at 7mpg, same RPM's. Long story, but if you plan tow I'd go ED all the way for the torque and lower RPM's and only with 3.92's, no 3.21.
Just towed with a 2020 laramie ecodiesel with 3.92's due to a relationship with a dealer. About 100km highway and 30km city. Averaged 14mpg with the same trailer above, almost double the mileage, no trans hunting and WAY more enjoyable driving. Undecided as the payload on the model I want is only 1430lbs vs my current 1390 on my 2012 and kids are growing. Might go 2500 cummins as the price is the same right now from 1500 to 3500 and about $20,000CDN more for the 3500.
 

Drewster

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TFL is one of the best 3rd party resources for towing MPG https://tfltruck.com/2018/06/mpg-challenge-most-efficient-truck-towing-listed-specs/

Without a doubt, the modern turbodiesel version of a truck will get better MPG than gas variants. If that's all you care about, you have your answer.

The thing to keep in mind is that diesel engines are considerably more complex than the gas variants. This Hemi has been around for ~16 years, and is probably the most simple, tested V8 on the market since it's still pushrod, still port-injected, while Ford seems to struggle with cam phasers and GM has the typical Direct Injection issues.

On the diesel, you have to drain the water separator, replace the fuel filter frequently, fill it up with DEF, and then keep in mind that the EGR, DEF, SCR, and DPF systems are all semi-complicated things that will keep the ECU from running properly in the event of an issue. Driving around town, it can be surprisingly hard to find a diesel pump. When we had our TDI, we found ourselves waiting in line because the only two diesel pumps at the station were taken up by families shopping for half an hour.

If you're towing every day or every weekend, the Diesel will likely make your life a lot easier. If you only end up pulling that camper once a year, the 5.7 will likely do that just fine but without the added complexity for the other 11 months out of the year.

Everyone buys trucks based on the "oh, well *eventually* I want to tow ____" but you should be really honest with yourself about how often you'll be towing the camper you don't even have yet.

I am still learning myself, but I agree that payload is a first limiting factor than towing capacity so I am most likely not getting 3.92 axle ratio. The main question that remains open for me is ED vs HEMI as I do not know how they perform when you pull a trailer. I guess the safest option is to buy a HEMI as it is a proven engine. I personally drove one for two years and enjoyed it. Towing consumption rate is another thing I am really interested to know. I am kind a bit concerned with the numbers 9-10 MPG I heard for HEMI.

If you plan on towing, this is terrible logic. If you play around on https://www.ramtrucks.com/towing-guide.html you'll notice that toggling a given configuration between 3.92 and the 3.21 doesn't change the payload, but it definitely changes the towing! Having the 3.92 will help you pull 100% of the time by putting more torque to the wheels, and when you're at speed with a load it won't make an MPG impact up or down since the 3.21 won't be in OD. Look around the forum and you'll see that most who tow a lot with their truck wish they had gotten the 3.92 and the bigger fuel tank.
 

JF19Longhorn

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Whichever you get, check the payload weight on the door sticker before you buy. It will be the true limiting factor in what trailer you can 'legally' tow.
 

WXman

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Whichever you get, check the payload weight on the door sticker before you buy. It will be the true limiting factor in what trailer you can 'legally' tow.

Truth speech and this is what almost no salesman will tell you. Payload is what you'll run out of on a midsize or fullsize "1/2 ton" truck first.
 

VernDiesel

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As a TT transporter with 725,000 miles on 2014 Ecodiesel truck, my focus for safety & stability is (My priority may not be the first priority of those focused on payload numbers) weight distribution of axle & tongue weights as seen by the CAT scale.

Not to exceed (5th gen) axle weights (3,900 for steer 4,100 for drive axle) nor 1,150 for the receiver.

Additionally & more specifically for safety & stability - replacing my trucks unloaded steer weight and adjusting WDH & loading towards a 12.0 percent tongue weight. (Of gross wet trailer weight.)

So personally I’m not very concerned with exceeding the 7,100 pound GVWR until it would additionally exceed an axle or combined axles weight. At least not as said for stability & safety.

Now as a consumer if my first concern is being pulled over by DOT and being put on portable scales and potentially getting a ticket then I might want to CAT scale my load so I’m not additionally over GVWR which would also be over the payload sticker number.

Hope that helps understand what numbers have what values to help you prioritize what is important to you.

Rau, Your trailer showed a dry weight of 5,700. Typically this translates to a wet weight of around 6,700 translating into an ideal tongue weight of about 800 pounds. If this held true your Combined axle weight of your loaded truck axles should be about 800 pounds more than the combined axle weight of your unloaded truck per your CAT scale slips.
 
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drmoreau

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I have a 2020 ED 4x4. I tow a 4,000 Airstream. I've done some long trips and typically get 14-15 mpg. I usually drive 65 mph, and back it down on long grades. The DRF usage is directly correlated to fuel burn, so of course it is going to go up, but the cost is minuscule compared to fuel cost. Something to remember is that doubling your speed requires tripling the power. So keeping the speed down makes a big difference in mileage, especially with headwinds. A final thought: Biodiesel is a surfactant and will clean your fuel system. If you have a lot of miles on your rig and start using biodiesel blends, be prepared to change the fuel filter after a few tanks of the biodiesel. My truck is still pretty low mileage so the biodiesel use is not loading up my fuel filter - the system is relatively clean to start with.
 

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