2001-early 2004 LB7 Duramax Fuel Economy Poll

[NeilLB7]

On a totally stock 2002 HD2500 Allison Ext Cab 4x4, all hand calculations, purchasing from the same station and pump, filling from 1/4 tank each time, using Stanadyne PF each fill up...I've come up with the following over the last 11 months.

Highest 18.85 MPG.
Lowest 16.90 MPG (I did alot of city driving this go-round and was a little heavy on the pedal at times)
Furthest Distance from 4/4 to 1/4 tank (fill up point) = 392 miles (I do not go below 1/4 tank as a personal preference)
19.878 gallons average purchased at fill up.
Total overall average MPG = 18.01
Average price per gallon = $2.629/gallon
Total miles represented to produce this data in 11 months = 13,233 MI

The truck has 142,000 miles on odometer, no modifications at all, original injectors, Mobil Delvac 1300, Mobil Syn gear lubes, Valvoline Dexron III ATF, Mobil1 5W-30 transfer case lube, OEM Bridgestone tires etc etc. About a 60/40 ratio of hwy vs. city driving. All empty miles, no towing. 65 MPH highway shows about 18-1900 RPM.

So...unless new injectors and such would really improve MPG's...I don't see how people get anything significant over 20 MPG Avg. My friends claim to...but they have zero data to support the claims.

Now keep in mind this is all average MPG's for me. Which is all I pay attention to. Because I'm buying diesel when my average driving empties the tank.

[npauli]

So...unless new injectors and such would really improve MPG's...I don't see how people get anything significant over 20 MPG Avg. My friends claim to...but they have zero data to support the claims.

It can be done, but not without really working at it.

I've got data over 15k miles with quite a few numbers over 20 (details below). The biggest difference is:
1) the manual tranny gets great efficiency to start with, and enables lots of special techniques to save fuel (like engine braking or the ability to coast in gear for zero fuel use or with the clutch in for minimal driveline drag).
2) I've been paying particular attention to driving for best fuel economy. It takes me longer to get where I'm going, but I burn less fuel on the way. If you saw me drive, you'd probably find the numbers below more believable.

15,697 miles (adding 3% to odo for 265 tires)
699.5 gal (from the pump)
22.4 mpg average
26.2 mpg = best tank
18.5 mpg = worst tank (never got above freezing, some cold starts ~ 0F)
12 months

I got just over 20mpg when I bought the truck in july 2008 (previous owner did too). I probably got 1-2 mpg more from using all synthetic fluids, and the rest is driving techniques.

[NeilLB7]

I would say that a regular cab manual truck could get better numbers than myself...and things of that nature. Thats understandable. Or even some tunes that are designed to increase economy will help. But I've got people with larger trucks, huge tires, no gearing changes, tuners, etc etc that tell some pretty good tales on fuel mileage.

I'd say that some instantaneous MPG's in my truck are really good considering my average. But again, I can't go by that because I dont drive like that 100% of the time.

My friend likes to brag about what the computer tells him at 60mph on the highway...as if thats the average he gets all the time. Yet I tell him that his worst MPG he see's on it is just as valid as the high MPG he sees. When he brags about getting 24MPG...I say he actually only gets 12MPG by the same method. His low is just as valid as the high to me.

We argue, he mumbles something, and we start talking about something else usually.