C&D 2019 RAM DT Long-Term Test

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43,062
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Ontario, Canada
Tundras get bad mileage for 2 reasons: 1. Not direct injection. 2. High output for 5.7 liters. The quality is worth the fuel bill, at least at 2.50 a gallon.
The HEMI is also 5.7L and not direct injected. It also has higher specific output (395HP/410lb-ft vs 381HP/401lb-ft). The Tundra is just hard(er) on fuel. I'd say The Critic's point about deeper gearing is probably bang-on, as that would definitely be a contributor.
 
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16,717
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NH
The deeper gearing is probably a factor--the pinion has to make that many more turns for each revolution of the tires. Looks like the ZF8HP70 runs 0.67:1 for 8th gear? Tundra runs 0.59:1 for final. 0.67*3.92 is 2.63 while 0.59*4.3 is 2.54. Tundra actually has a taller final drive (for the 3.21 RAM's it would be 2.15).

I wonder what the fuel burn is at idle. Just seems like, over the years, Toyota's smelled rich on cold starts. Completely anecdotal, just what the sniff test tells me in parking lots at work, during the mad dash to leave at the end of the day.
 
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1,961
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Tri State Conservative
Tundras get bad mileage for 2 reasons: 1. Not direct injection. 2. High output for 5.7 liters. The quality is worth the fuel bill, at least at 2.50 a gallon.
"Not direct injection." The 7.3 L doesn't have that. I'm guessing the stone aged trans instead.
Tundra also runs 0w20 and the Ford 5W30
In the end they all are gas hogs
 
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2,467
Location
utah
Yes, the 7.3 gas will pay a fuel penalty for not using DI. But it gains durability and won't ever need any deposit cleanings. Its a real tank engine. I won't be surprised years later to see people get 500k miles out of a well cared for 7.3L. They will support a small oil producing nation along the way but their engine will be good. Probably the smartest decision for fleet truck buyers is go indestructible. If i had to buy a gas HD truck i would prefer the 6.6 GMC because it will eek out slightly more per gallon than the 7.3 and i wouldn't mind the eventual maintenance. I also wouldn't need it to last 300-500k miles.
 
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9,522
Location
Ontario, Canada
The deeper gearing is probably a factor--the pinion has to make that many more turns for each revolution of the tires. Looks like the ZF8HP70 runs 0.67:1 for 8th gear? Tundra runs 0.59:1 for final. 0.67*3.92 is 2.63 while 0.59*4.3 is 2.54. Tundra actually has a taller final drive (for the 3.21 RAM's it would be 2.15).

I wonder what the fuel burn is at idle. Just seems like, over the years, Toyota's smelled rich on cold starts. Completely anecdotal, just what the sniff test tells me in parking lots at work, during the mad dash to leave at the end of the day.
I always get the impression toyota leaves a little more margin for abuse on their design/tuning for drivetrains. They don't chase extreme mileage or power, but go for reliability and burn a bit more fuel. They seem to avoid stuff like RAM's eco-diesel problems...
 

The Critic

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22,305
Location
CA
I always get the impression toyota leaves a little more margin for abuse on their design/tuning for drivetrains. They don't chase extreme mileage or power, but go for reliability and burn a bit more fuel. They seem to avoid stuff like RAM's eco-diesel problems...
In general, I have noticed that Toyota's engineering philosophy is to overbuild where it matters....and usually that is where the consumer doesn't see (under-the-hood).
 
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...
View attachment 28726
Thats my truck, adjustable BDS lift with just enough to clear those michelin 35x12.50x20s. It runs dead silent and smooth down the highway. It's got a diamondback hard tonneau cover not sure if thats helping or hurting aero. When i say it gets 19 mpg, it really does, and thats at normal highway limits of 75 mph. If one were to roll down a slow 2 lane of say 50 mph, it could pull that in 4 cylinder mode and average something in the 30s. 40 mph? 35 mpg easily on 4 cylinder. Its the SLT trim but not heavily optioned, no sunroof, just the 6.2, NHT max tow, and the slightly upgraded NAV radio but no bose.

Do you have a load in the back?
 
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2,467
Location
utah
Do you have a load in the back?
For my truck (or van, i usually haul with the van) it is usually unloaded one way and some load on the way back, 100-600 lb maybe. OR it is used for like a family camping trip type thing where it is fairly loaded down both ways. I haven't had to load on top of the diamondback yet but it is rated for that. That sort of load would hurt the aero a lot i'm sure. I don't think a few hundred pounds in the enclosed bed area matters much on highway runs. City stop and go would be a lot more of an effect.

Edit: The diamondback cover itself adds weight, maybe 100lbs. The BDS lift kit and its longer springs in the back is probably adding 150lb over a stock truck. The larger tires might add 40lbs.
 
Messages
43,062
Location
Ontario, Canada
I always get the impression toyota leaves a little more margin for abuse on their design/tuning for drivetrains. They don't chase extreme mileage or power, but go for reliability and burn a bit more fuel. They seem to avoid stuff like RAM's eco-diesel problems...
Indeed, so it is interesting that they've had so many issues with their 8spd transmission. Recall StevieC offloaded his Highlander due to that transmission.
 

JTK

Messages
12,993
Location
Buffalo, NY
- Cracked Exhaust Manifolds. FCA made some revisions to the Exhaust Manifolds and Studs on the 2019+ Ram DT’s. The design is slightly different from the older trucks. The bolt breakage issue is somewhat less common but instead, the manifolds now crack for some unknown reason.
I wonder if my 2019 classic has the new style manifolds and mounting studs.. Interesting.
 
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8,315
Location
Texas
My RAM Limited 4x4 is giving me 17.9 but most of my driving is freeway and I don't hypermile it at all. I think I could squeak out 18 maybe 18.5 if I drove the speed limit. When towing my car hauler with a car or my RV it will drop to 15. My Sierra Denali AWD barely gets 13 in the same driving conditions....towing drops to 11. Of course the Hemi can run in 4cyl mode where my Denali can't - its an 06 with the LQ9 6.0L.
 

The Critic

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22,305
Location
CA
My RAM Limited 4x4 is giving me 17.9 but most of my driving is freeway and I don't hypermile it at all. I think I could squeak out 18 maybe 18.5 if I drove the speed limit. When towing my car hauler with a car or my RV it will drop to 15. My Sierra Denali AWD barely gets 13 in the same driving conditions....towing drops to 11. Of course the Hemi can run in 4cyl mode where my Denali can't - its an 06 with the LQ9 6.0L.
Took a drive from Sedona, AZ, to Scottsdale, AZ yesterday on I-17. 80 mph whenever possible and the oil temp reached 240F at times. The return trip yielded lower numbers but the trip average was 21.5. The onboard computer is fairly accurate has never been off by more than 5%.
 

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