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Discussion Starter · #1 ·
Background: 2008 6.7lt, 6 speed auto, quad cab, 4x4, short bed, 100% stock, 3002 miles on the odo.

My 108 mile round trip today, netted me a total of exactly 20.0mpg(according to the computer deal overhead). It clicked 20.0 as soon as I hit my community, and back down to 19.9 after 2 miles of slow traffic until I arrived at my driveway.

Cruise control was used on 90% of the trip, and all 90% was highway, the remaining 10% was slow city driving @~10-35mph.

For the rest of the 92(ish) miles 50 miles was traveled at 65mph. 30 miles was traveled at 75mph, and the remaining 12 was traveled at 55mph.

Again, this is brand new 2008 with all the emissions BS. I have to say I'm pretty happy considering my mpg is *suppose* to increase @10k miles.

The 108 mile round trip is just my commute to work and back, and I plan on keeping a record of any trips I make over 100 miles and if ya'll want I can post results here. I expect to see some nice numbers as my mileage climbs and I begin to add intake/exhaust, and remove DPF/EGR(if I remove them at all).:peelout
 

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Be sure to hand calculate the numbers. Some overhead displays are WAY off. Hopefully your's is right on. Those are good numbers! My overhead reads like 2 or so better than what I'm actually getting.
 

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The overhead is a lie-o-meter just to make you feel better. Hand calculated my mileage is typically 1.5 to 2 mpg less than the overhead. The trip you took was not that long and the truck may not have went into regen during the trip. If these trucks would not have to regen I think the mileage would be quite good. If you reset the overhead when the truck is in regen the ovehead will show the milage as 13-14 mpg. Since the overhead is inaccurate mileage during regen is 11-12 mpg. Regen usually takes 20 minutes or a little longer in my truck.
 

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Discussion Starter · #4 ·
Be sure to hand calculate the numbers. Some overhead displays are WAY off. Hopefully your's is right on. Those are good numbers! My overhead reads like 2 or so better than what I'm actually getting.
I thought about that, and even still, wouldnt 18mpg be pretty nice for a nonbroken-in truck?
 

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Discussion Starter · #5 ·
The overhead is a lie-o-meter just to make you feel better. Hand calculated my mileage is typically 1.5 to 2 mpg less than the overhead. The trip you took was not that long and the truck may not have went into regen during the trip. If these trucks would not have to regen I think the mileage would be quite good. If you reset the overhead when the truck is in regen the ovehead will show the milage as 13-14 mpg. Since the overhead is inaccurate mileage during regen is 11-12 mpg. Regen usually takes 20 minutes or a little longer in my truck.
I think i was in regen at some point in there. Is there a noise or any kind of notification of regen? maybe a loss of power or something?
 

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There is really no way of knowing when your truck is in regen cycle unless you have some type of pyrometer. Of course the overhead will let ya know if your DPF is like 80% full or higher and it will let ya know it's going into an active regen process. Basically, if you see the ol' MPG's heading south for no apparent reason, it's likely you're in regen cycle. It'll stay there for about twenty to thirty minutes, then start creeping back up a little.

I hit regen on a return trip at a very inopportune time. Climbing a mountain at 75mph w/ a 45mph headwind! Dropped to like 12.5! :thud:

Oh, and.......:welcome:
 

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The overheads are usually pretty correct, one major thing to consider is tire size. If you change any aspect of tire height it will be off
 

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I agree, not exactly 100% accurate but for a estimate they are perfect. They let you know if you are using more fuel than normal or less. It is in essence an extra gauge, because too much fuel will burn up a motor just as easy as not enough.
 

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I am driving about 700 miles a week mostly hwy and getting 18.5 MPG, so I am pleased, I drive the speed limit...
 

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Discussion Starter · #13 ·
I drive the speed limit...
This.

Just screwin around on the roads, driving 50 miles one way the speed limit, then back the other way 5-10mph over was a substantail differance, about 2mpg. Again though, this was according to the overhead thingy. Next time i fill up i will do hand calc. the '08 2500s have 34 or 35 gal tanks??
 

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With the regen on the 2008, do you have to be operating at a certain speed to complete the cycle? I've had some guys tell me on the 07s this was the case. I'm encouraged by everyone that posted here with the 08 mileage, looking to purchase one soon.
 

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Can someone point me to a post that explains this "regen" thing you guys are talking about? I'm feeling really stupid right about now. What the hell is it? Is it part of the emissions crap? EZ on the noob!:eek:hno:
 

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Long story short (you can google it for the various long versions) a regen cycle is when fuel is injected during the exhaust stroke to 'heat up' the exhaust to the point where the DPF assembly becomes an incinerator and burns off all of the accumulated stuff / soot that is being filtered.

The process is far more complicated than what I just described but the extra fuel injection cycles are one of the leading causes of both poor fuel mileage and fuel dilution of the oil aka 'engine making oil'
 

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count your blessings fellas i get arround 10 in town and 14 on freeway
 

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What year of truck does regen happen on. Just the 08's or some other ones. My overhead usually reads 20.5 to 21mpg but if I hand figure it. It is usually about 3mpg less. Was a little let down the first time I figured it by hand. But, then again I did not buy a 1 ton 4x4 truck for the fuel milage.
 

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Long story short (you can google it for the various long versions) a regen cycle is when fuel is injected during the exhaust stroke to 'heat up' the exhaust to the point where the DPF assembly becomes an incinerator and burns off all of the accumulated stuff / soot that is being filtered.
Afterburners..... :popcorn:
 
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