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Old 07-31-2019, 10:27 AM   #11 (permalink)
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Quote:
Originally Posted by rmay635703 View Post
Generally the fewer cylinders the more efficient due to thermal loss and friction, odd cylinder counts get better FE due to harmonics, a 3 cylinder 2.2 liter diesel would be the most efficient while also being harsh to drive.

Anyway.
At this point the economy isnít ďbadĒ comparatively on any of these trucks (if you look back 10 years anyway)

That said my 6.2 suburban could turn 28mpg with a 5 speed stick, and it was cheap and didnít require a turbo (which tends to plug up in cold climates)
I was saying 'bad' relative the to the larger displacement engine in the heavier Silverado. I'm really curious as to why it is the way it is.

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Old 07-31-2019, 11:38 AM   #12 (permalink)
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Quote:
Originally Posted by rmay635703 View Post
Generally the fewer cylinders the more efficient due to thermal loss and friction, odd cylinder counts get better FE due to harmonics, a 3 cylinder 2.2 liter diesel would be the most efficient while also being harsh to drive.

Anyway.
At this point the economy isn’t “bad” comparatively on any of these trucks (if you look back 10 years anyway)

That said my 6.2 suburban could turn 28mpg with a 5 speed stick, and it was cheap and didn’t require a turbo (which tends to plug up in cold climates)
Road and Track got 43mpg with this truck keeping it under 60 mph. Being able to get 28mpg and getting a modern EPA rating of 33mpg are two very different things. This truck really puts to shame any full size ever made before and the Ram is supposed to be even better. Wasn't that long ago an epa rating under the current standards would be less than 1/2 what this gets. That's like a Malibu going from 35 mpg to 70 mpg epa rated in 10 years time.
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Old 07-31-2019, 11:47 AM   #13 (permalink)
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Quote:
Originally Posted by Shaneajanderson View Post
That's a big four banger. Not sure why that would get such bad fuel economy, though admittedly I know little about diesel engines.
A lot of it may have to do with the 2.8 gets a 6 speed and the 3.0 gets a 10 speed. I also suppose more smaller cylinders may be more efficient at complete diesel burn than fewer larger cylinders even though you have 2 extra sets of rings and a few more bearings. I know emissions was why Dodge went from making the 440 big block V8 and made a 500 ci V10 instead. They just couldn't get a clean burn on the big holes. Then again that was 20 years ago and everyone is coming out with big gas motors again so it think with modern direct injection and variable cam timing just about anything is possible.
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Old 07-31-2019, 12:26 PM   #14 (permalink)
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Quote:
Originally Posted by Shaneajanderson View Post
I was saying 'bad' relative the to the larger displacement engine in the heavier Silverado. I'm really curious as to why it is the way it is.
Usually it comes down to the following

1. Aero
2. EPA MPG Crossover speed (this has the greatest effect on real world economy not “as tested” economy which at times is almost meaningless when comparing two vehicles with similar economy values)
3. Transmission efficiency and controls
4. DEF efficiency and controls, dirtier engines drive more regen.


It is very worthy to note this Silverado only scores 23mpg city and 33mpg highway.

The epa combined value for me is almost meaningless , the fact PHEVs rarely mentioned city and highway separate was a big red flag for me.

We shall see what the real world reports once these are on the road a few years, I doubt 40mpg at steady slower speeds will be commonplace but who knows?
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Old 07-31-2019, 01:40 PM   #15 (permalink)
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33 highway seems impossible. How'd they get a large brick to return that fuel economy? How did Road and Track get 43 MPG? That's what a Fusion hybrid gets. I realize diesel is good for about 20% more energy per gallon, but still.

I drove straight and steady at 55 MPH once in my truck and got something like 22 MPG. Granted my truck needs major front end work, the transmission is letting go, and I've got large off road rated tires, and the headache rack sticks above the cab.
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Old 07-31-2019, 07:01 PM   #16 (permalink)
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Eh, I could see 43 mpg in a one-off test. Things like the deep air dam, wheel strakes in front of the rear wheels, very tall air curtains on the front wheels, roof curvature and trailing edge shape, streamlined mirrors, body shaping around the A-pillar and doors (I think that's more than cosmetic on this truck), tailgate spoiler design, all add up. Then add in the 10-speed transmission, the increased efficiency of the diesel, (probably) optimized cooling air inlet size, etc. compared to your truck--I could see it.
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Old 08-01-2019, 06:49 AM   #17 (permalink)
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FWIW, I can push my stock 305HP/555TQ Ď04 Cummins 1T along at just over 30-mpg with close to 1K additional weight above published shipping weight (just under 8k) if I keep it under 55mph on level terrain with no adverse winds in mild temperatures.

This is for more than fifty miles and understanding the correction factor for the overhead MPG display.

My truck was built in August of 2003. If big trucks are any comparison, an Ď03 model versus a 2019 model are leagues apart in computer drivetrain control finesse; even where specification appears the same.

So a 2020 Detroit pickemup with high MPG numbers shouldn't be surprising. Contemporary comparisons showed me my MPG wasnít different against a dozen others in trailer towing, a 40% correction factor means most were seeing 23-mpg or better 62-65/mph while solo.

A 10-speed auto trans, variable-vane turbocharger-equipped I6 diesel is one VERY sophisticated creature.

The flaw in thinking about pickups is in considering them as family transportation. With no IRS depreciation and/or deductible miles, this pickup or others is one BAD choice.

Where high annual business miles apply, the premium and the return on investment are both within scope.

Diesel doesnít pay off until 200k miles. And then it is the hope that the drivetrain will continue to lifeís end without rebuild. Which will not be true for a gasser. Thatís a window which takes planning and discipline.

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Old 08-01-2019, 12:56 PM   #18 (permalink)
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The other good thing about this Silverado is the 6.2 gas and 3.0 diesel are both priced the same. About $2500 more than the 5.3 v8 so it should pay for itself much sooner than a $5-6k Cummins upgrade. The good thing on the Cummins you can usually get back almost all that at resale compared to a gas Ram.
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Old 08-01-2019, 01:54 PM   #19 (permalink)
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I noticed diesel a few cents cheaper than regular the other night. First time I've noticed it cheaper in perhaps 15 years. Diesel used to always be significantly less back then.
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Old 08-01-2019, 02:42 PM   #20 (permalink)
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I noticed diesel a few cents cheaper than regular the other night. First time I've noticed it cheaper in perhaps 15 years. Diesel used to always be significantly less back then.
When we drove to the coast I noticed both Oregon and Washington had diesel under unleaded, but in Idaho and Montana it is higher. It wasn't the diesel that varied a lot in price, it was the gas. So Oregon and Washington just have high unleaded prices and average diesel prices.

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