Cummins "secrets" on better fuel economy paper
 

Not to many secrets here but a lot of what affects what, and by what %. It is about 18 wheelers, I don't think cars have that kind of rolling resistance.
https://cumminsengines.com/uploads/d...whitepaper.pdf

Great find. There is stuff in their that can help drivers regardless of gross vehicle weight.

They address changes in RRc , and CdA separately and very helpful.

It's interesting to see their numbers for road surfaces. I chuckled at driver satisfaction being on the opposite end of the teeter totter of owner satisfaction. Load based speed control is surely something familiar to us Insight owners, albeit in manual mode for us. Something automatic to stay in lean burn would come in handy.

I think the freelance guys would learn a lot from this. I'm not sure what business they're conducting, but most of the time on the interstate it will be trucks that look like show trucks speeding the most. Crazy paint jobs, polished stacks, lights all over, older boxy trucks with zero aerodynamic aids.

The graph that shows raising tire pressure from 100 PSI to 120 PSI makes for a 2% increase in MPG made me LOL and realise what I've been doing wrong all the time ;)
(of course those wheels endure over 10 times more weight than mine)

Kenworth has one similar. I've recommended both several times over the years at this site.

Prominently, while vehicle spec has first place in understanding FE of a particular vehicle, comparisons to others (once past tech spec) is that

Climate
Terrain
Driver Skill

Are necessary

On RV forums, I searched for and found about one dozen comps to my truck and travel trailer. Same brand and motor. (Not otherwise as to spec). TT type had to be aerodynamic, all aluminum. Length from 27' to 35'. Weight from 7k lbs to 11k. Then, that the users making reports had to be in the South Central US. And travel speeds of 65-mph or less. Only then could I make an assumption that my FE of 14-16/mpg was normal.

Generally ignored are important considerations such as steering inputs per 100 miles. That KW and Cummins call them measurable should be a wake up. Especially with a 4WD and/or towing.

In another thread (and something I've brought up repeatedly) one needs a handle on solo mpg where the vehicle is loaded as if for towing AND is covering the same sort of climate/terrain AND at the same speed as if towing. Why? Because whether the testing was conducted in 1966 or today in 2016, the percentage FE drop is right at 40% given a speed of between 60-65/mph.

An aero trailer CAN be lower. Maybe trending towards 30%. Even lower is possible where the driver has route familiarity AND knows how to plan. I've done it with a UHaul no taller than the cab height topper on my truck bed. 25%. Twice, over the same route.

The KW and Cummins White Papers are aimed at revenue miles. Thus, in the final category of differences between drivers, a difference if almost one third is present. Same equipment, same load and same route.

This is the focus around here, in general. But I'd argue that much more attention to mechanical details is first. 40 will never be 30 if alignment on both vehicles isn't perfect. Same for brand drag on both. Same for book maintenance otherwise. Brand new vehicles aren't exempt from verification.

So, take your vehicle and load it to manufacturer maximum. Sand bags or whatnot. Learn to drive it well. Earn your stripes. This IS the design parameter, NOT solo driver.

Can't afford maxed air pressure tires, but load/pressure balanced. One cannot afford loss of handling traction, much less braking traction. Etc. A CAT Scale is an easy way to learn to load it. Look for differences cross-axle, as well. The heavier wheel position on the axle determines cold pressure setting.

I just came out of the main terminal shop. They worked me right in to correct the starboard toe alignment (off 1/16). They'd have laughed were my complaint about my AC being too warm. That's a preset interval check (PM, as it's known).

That my KW now tracks straight -- and tire ruin averted -- goes straight to the annual average mpg. I'm not having to scan the changing road surface as diligently. Won't jump around in the lane, now.

It applies to your air conditioned go kart. But you'll fix the AC first, right?

Load it to maximum and re-learn HOW to drive it. There's no real end to skill acquisition. It pays. There is no worthwhile education if done at the last moment. It's part of owning a piece of equipment to know how it operates under all conditions. Around here, we test.

Thanks Slowmover, I couldn't find a date on it and figured it might have been posted before. Watching commercial truckers seems to make me think they don't buy their gas. Then again with any car out there, the poor drivers always stand out in your mind. Like the Prius drivers are slow claim. There are probably 100 trucks you see that don't register in your brain, and it's not till you see that one you think all truck drivers are bad. If they don't already, companies should give bonuses to the drivers who save the most fuel. At least let them have the extra money from the fuel cost, but they are also saving wear and tear and probably much less likely to have an accident.

Slowmover, on a somewhat related note, the reason I found this was I was trying to figure out what Dodge Cummins has the best potential for high fuel economy. Your 2004 seems like a good bet. I need a bigger cab then the 94-02 offers, unless there are crew cabs out there I don't know. I'm not above a swap into a Ford or Chevy either. I'm also OK with whatever mods might help, no emissions here and I don't want to make big power, just like a DPF and EGR delete for economy and reliability towing about a 6-7000 pound travel trailer.

My 14 mpg towing that Hi-Lo has gone to 9 mpg with the new Forest River hybrid. I don't think that's unexpected. I'm also thinking about a 2008 3.0 GL Mercedes CRD but I don't want the rest of the expensive problems that surround those things. The Ecodiesel Dodges and Jeeps are just too expensive still.

Cummins 6BT MPG:
1 dont grind on the fuel pin or plate.
2 aero, like narrow tires and lowering, fold mirrors in, Moon discs on wheels
3 overdrive with 3.54 axle, or better yet swap a 3.21 rear
4 replace stock turbo with something more efficient, as in more charge at lower egts at cruise
5 more efficient intercooler
6 Banks intake elbow casting
7 dont do huge exhaust, just a better flowing muffler
30 mpg is probable.

Most truck companies have some form of incentive as to fuel use. This is past the large number of trucks you'll encounter which are limited to 65-mph, sometimes less. (Not all of those do a good job with the drivetrain. Those that do have trucks that barely slow on most grades). Time is important. And the daily average miles needs to be high for a driver to earn much. The lower level life form truckers -- pulling vans -- waste ungodly amounts of time at shippers and receivers. Something the Feds should have into long ago. Same for drivers having to load or unload their trailers. IOW, truck travel speed isn't a determinant entirely, of daily pay.

The ones who run very fast --above seventy -- are likely owner-operators who've learned the intricacies of hoe not to go broke driving a truck. Unless you see the same truck passing you repeatedly, it may be he's trying to move along to get thru that major metro area ahead before evening rush hour. Or, deliver today versus tomorrow. The net difference comes directly out his pocket. And it's more than fuel. It's a truck that wears out faster.

The usual fuel incentive is to control idle hours. If the company has equipped the truck with an APU, then the savings on the big motor are substantial. Otherwise, (as with my Cummins powered Kenworth T660, a Webasto bunk heater is installed). Those of us from the southern terminals have a greater idle percent time in the heat. Those up north, in the winter.

My truck has used 172,000+ gls over its 790,000-mile life (2010 model, means it went into service late 2009). 5.555-mpg average according to the computer. But we also idle up to use a big-ass blower to either vacuum product aboard, or switch the plumbing around to power it off a 1600 c/f pneumatic aluminum trailer. 1.5-2.0 hours to load and a little less to unload. (With some freakish loads. Once spent 27-hours loading).

The ones to watch out for are the biggest firms (Schneider, Hunt and especially Swift) as the drivers are notoriously poor. Those boys get raped. Slow trucks and not enough miles to make any money. Werner can be another. Starter jobs. Slow trucks usually. The one I watch out for the most are the Fed-Ex contractors pulling doubles and running team for a small fleet owner. Same route over and over. Contempt, due to that familiarity (take chances they shouldn't).

Truck spec for the job is vital. Huge. Gigantic. Get that right and the FE numbers fall into place.

An example of a firm pushing FE is Mesilla Valley out of El Paso. First ones with skirts and tails. And an extensive fuel bonus program. Some one running super singles is trying for the same (hate those things. Bad traction and when they blow it's awesomely destructive. And then the rig is stranded.).

More than anything, stay the hell away from big trucks. It isn't hard to do. Most are at 65. They'll bunch up. A few others are faster, but not many.