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Old 06-24-2019, 05:31 AM   #5 (permalink)
slowmover
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Join Date: Oct 2009
Location: Fort Worth, Texas
Posts: 2,442

2004 CTD - '04 DODGE RAM 2500 SLT
Team Cummins
90 day: 19.36 mpg (US)
Thanks: 1,422
Thanked 737 Times in 557 Posts
Not enough specifics to know how 40 was hit. Least amount of throttle changes also means preventing brake use. It’s knowing how to glide. (A/C off is funny. And unnecessary)

The real secret is that with a 10-speed auto trans and variable-vane turbocharger that drivetrain software programming is mature to the point that MPG figures from just a few years ago are no longer relevant.

The 2019 Peterbilt I’m in is set for a van aerodynamically. 13L PACCAR I6 and 12-speed PACCAR Automated Manual. Bobtail, with maximum fuel (220-gls), driver & drivers gear this tractor scales at 21,500-lbs. (Extra insulation and an 8-battery setup that uses [4] AGMS to run sleeper A/C).

With no adverse winds I can run the Interstates while bobtail out on the Plains at an indicated 14-mpg at 67-mph at the usual 1,150-rpm cruise. I’ve a friend with a fairly recent Duramax Silverado does that same mileage. A 9k pickup with a 6.6L engine & six speed.

With an aero package van and barest tailwind — plus 30k in the box — I can be in double-digits.

The difference between the 10-speed 2015 I was in and this one is impressive. It’s just THAT much better at every transition. It’s not quite enough to say that the trans is the biggest difference for that pickup.

And FWIW, the C&D comment about more for less (9,300-Tow Capacity) has for the likely RV owner/buyers a thump to the head about today’s granite-counter, slide-out junk bad-aero boxes that WEIGH TOO MUCH.

My 1989 35’ Silver Streak weighs less than the TEN FOOT SHORTER current Airstream 25’. The aero problem for both is fixed, but there’s almost nothing to functionally justify this piggish weight increase.

Similar to this half-ton in power, my ‘04 Dodge at 305HP/555TQ is vastly overpowered for the job of moving this 17 to 18k pound combined rig down the highway.

Being slower on the ascents is only a problem for the pussies.

I’d guess this truck, like the Dodge V6 diesel, is going to be wound pretty tight. Always on the job. Wholly unlike my Cummins Six.

Reading PERCENT ENGINE LOAD and never exceeding 80% is where a true-er test would start. This type of programming (and gearing choices available) will put it to the wall almost immediately. Would be best to forego that solo. And learn when to use and NOT to use while towing.

The reason for 13,15 & 18-gear transmissions in big trucks was to keep the engine in the sweet spot. Always. Road speed didn’t matter very much (relative to acceleration rate).

We’re going to hear “lousy” numbers from those who can’t be bothered to learn how to solve the problem by adjusting their bad habits. It’s all about feelz these days. And it’s embarrassing. “Men” with the fortitude of women or minorities. (The Churchill quote about, you’ve never really been to war unless you’ve fought the Germans. Yes, for problem-solving, the NCOs and enlisted were given goals. And left to achieve them).

The most for the least isn’t up to the vehicle. And an empty pickup isn’t any test at all.

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Last edited by slowmover; 06-24-2019 at 06:26 AM..
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