251 Consecutive >30 mpg Commutes

[Diesel_Dave]

Technically, I guess this could be called a "Failure Story", but I'm going to foccus on the positive.

Friday night was the first time I've had a <30 mpg commute since the end of May. Now, keep in mind, the mpg number is based on my in-cab display, which is rather optimistic (~15% high typically), so 30 mpg is actually something like 25.5 mpg, but I guess it's a psychological thing to see a number in the 30's.

I started my FE quest about March and the end of April was the first time I had a commute over 30 mpg. I started my daily log on May 10, typically averaging about 28 or 29 mpg. With some better routes, some hypermilling, and a few mods, I'd gotten my average up to the mid to high 30's by late fall.

The cooler weather has taken it's toll and recently my average has dropped to the low 30's. My evening commutes are particularly bad, because I can't plug in like I can in the mornings.

So anyway, I got 29.9 mpg on Friday night. The freezing temperatures, some gusting headwinds, and catching a couple lights badly all led to my streak being broken.

All in all though, considering what I drive I gotta be pretty pleased :-)

[slowmover]

Congratulations! Will be interesting to see when it comes back up. How are you figuring local temps to chart or graph, as your skill plus continued mods will affect mpg?

I'm not too far off from being able to re-fill tank at will instead of partial fills. Might spring for a winter cover depending on commute. TX_dj has me sold on an Ultragauge. Ever since you've started the Team Cummins group I've dialled back on shift rpm (DD is never over 1600, I tell myself) and gotten used to catching the next gear by 1,100 instead of 1,300. The overhead tells me I'm better, but . . . .

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[Diesel_Dave]

Originally Posted by slowmover

Congratulations! Will be interesting to see when it comes back up. How are you figuring local temps to chart or graph, as your skill plus continued mods will affect mpg?

I'm not too far off from being able to re-fill tank at will instead of partial fills. Might spring for a winter cover depending on commute. TX_dj has me sold on an Ultragauge. Ever since you've started the Team Cummins group I've dialled back on shift rpm (DD is never over 1600, I tell myself) and gotten used to catching the next gear by 1,100 instead of 1,300. The overhead tells me I'm better, but . . . .

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Thanks, slowmover! As far as when it will come back up, the 29.9 mpg was just a one day thing. I'm still averageing about 34ish on the lie-o-meter (averaging good days, bad days, mornings, evenings, etc). Back when it was warmer I was averaging up closer to 36-37 or so. In the last month or so the temps have averaged in the low 30's--that doesn't help. A couple days ago, it warmed up a little for about 2 days (temps in the 50's). Sure enough, for those 2 days I got quite a bit better FE.

I get my temperature data from a local weather station on the Weather Underground site (it really is a weather site--not the 1960's terrorist group ), They have stations all over the US and you can look up historical weather for any day you want (temperature, pressure, humidity, wind speed & direction, precipitation). I've kept a record of every commute since April in a spreadsheet with the weather data, as well as comments on changes I made, mods, route changes, etc. If you're interested PM me your email address and I'll send you the Excel file.

Didn't know you got the Ultragauge from TX_Dj. I knew he was having some trouble with it. I guess he gave up(?) I need to get one but haven't yet. Maybe here soon.

As far as the shifting goes, I guess you'll just have to wait until you get to the pump to find out for sure. I've learned shifting is kind of a habit thing--once you've done it one way for a while it takes some concentration do adjust your normal routine. Let me know how it turns out.

Edit: Just re-read your post and saw TX_Dj sold you on an UltraGauge, not sold you an UG,

[slowmover]

If you're interested PM me your email address and I'll send you the Excel file.

PM sent


As far as the shifting goes, I guess you'll just have to wait until you get to the pump to find out for sure. I've learned shifting is kind of a habit thing--once you've done it one way for a while it takes some concentration do adjust your normal routine. Let me know how it turns out.


I'm quite confident the mpg will have improved, that is almost beside the point for me in some ways. I really do need the U-gauge (or similar) to tell me about shift transitions. As to driving changes, I'm in Direct just before 30-mph now. Before I was simply using rpm to guide shifts, as in, a working range of 1,700-1,900 rpm which told me (based on a number of factors) which gear to be in. Even if I was running 33-mph in a 40-mph zone. Now, just keeping rpms as low as possible and an even lighter foot on the throttle . . it's too easy to lug the engine. Granted, a V8 Ford or GM would have a time of it, but even an L6 CTD can pull down too low at times (for my level of comfort).

That level of comfort has to do with always thinking of the truck as loaded, and towing so as to keep shifts and other driver inputs or motions consistent no matter the actual configuration. The "habit". I dragged a 7k trailer back to the house the other day and was pleased that so little change was needed in re shifting, throttle work, etc.

Solo miles may rule, but they don't pay the freight for what the truck is best at doing, it's raison d'etre. Longevity first, reliability second and FE a rather distant third. But TEAM CUMMINS done got in the way, so . . . .

Thank you for sending the Excel file at your convenience.

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[Diesel_Dave]

I just sent you the Excel file.

As far as the shifting goes, I agree completely that you need to do things differently when you're actually working the engine. All my previous comments assumed unloaded (which most of my miles are). When you're getting low enough with the rpms that you're getting close to the torque then you gotta shift up. When unloaded it's hard to lug the engine even if you're trying (400+ lb-ft of clutch engagement torque). Loaded is a different story.

[tylermj23]

Wow congrats