Turtle n Peeps wrote:
The 6-auto still doesn't have the 6-manual beat when it comes to diesel fuel mileage. Not with the right driver. Some of us value lowest operating costs, and fuel economy is one measure of that (along with tire & brake life, etc).
Any links to back that up?
My own experience driving oil field hotshot in 2010/11 1T and C&C trucks with goosenecks; a 6-auto and a 6-manual. And in discussion with others in the same game. Grossing over 30k day in and day out. Stop & go is where the difference is largest (for a given comparison). Loading at same customer to deliver to same consignee. Same route, etc. And seeing where things stand at fuel-up.
The 6-auto is easier, sure. Feathering the throttle works fairly well with an auto, to let it upshift with the least amount of throttle opening for a given road, load and traffic. But there are still places where when and how to shift still mean more. It adds up with a lot of miles. An auto isn't too good on the unpaved lease roads. One is on the brake too often. Not so with the man trans. Especially in slow maneuvering around a yard or at a rig. That's the auto penalty writ large.
Control matters when one is counting tenths. On the highway from one Interstate exit to another is probably is a wash. But these are trucks and they are expected to work. So not all roads are paved, much less smooth or with good traction.
The highest mpg average I know of is a CUMMINS engineer in his daily commute to work. Around 20k miles in 2012 at an
average of 40.5 mpg in his 6-manual 2008 truck. Highs near 50.
The average on my 305/555 is only 21-mpg the past 40k (and I'm back to running Class 8 around the oilfield). But I can hit 23-mpg consistently inside the city limits when I push it. I settle for 19+/- as it is easier. On the highway I don't fall below 24, and have seen 27 any number of times (on a dead stock truck; now at 7,900-lbs & 191k miles).
I've averaged 15+ mpg while towing the travel trailer. I am aiming at high 16's / low 17's for the future with my 35' TT. Chasing down mechanical details on both vehicles is this years plan. 25-cpm fuel cost ($4/gl) is fine, but it's fun to try to get it lower (non-mountainous terrain and non-extreme climate assumed).
Folks think that high mpg is either some form of magic or just lying. But then, they've never tried to do it, or to learn from others, either. Ergo, it can't happen (must be the "thinking").
Who'd have believed a 4-ton pickup could run a 12-second quarter mile and still be streetable not so many years ago? Not me. In that same vein, with the right driver, truck spec and determination, very high fuel economy is also possible. The 6-manual is at the heart of that, for now (behind a Cummins, the other brands aren't competitive).
I "assume" an 8-auto and tighter programming will change this.
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