OT: Real world Diesel Mileage?

Rod

Rod

1997 F250 7.3 DIT 4x4 4.10 gears city or hiway 16 mpg doesn't seem to matter.
2005 F350 6.0 PS 4x4 12 town 17 empty on the hiway 75 mph/Cruse control, the F350 has a lot more guts than the F250 does.

Below is a cost comparrision I did for RV.net about 3yrs ago. I think it has good real world numbers for RV use.

This was written about 1/1/03 and reflects my numbers gathered from the model years 2000 to 2002, 7.3 PSD and V10 engines. It appears all current (2004 model) diesels, PSD, CTD and the D-Max have slightly improved in fuel mileage since that time.

Note my savey insight into predicting the current price of fuel... :)

Where did I get my average mpg numbers? I got them from reading numerous mpg threads on many different forums over the past 4yrs and should be a pretty consistant fuel mileage average from reports of people who use miles driven divided by gallons used, a known accurate method for computing fuel mileage.

They did not come from anyone using the factory computer to report fuel mileage as some puters are off quite a bit. How? Example; engines being chipped are known to have extreamly high false mpg numbers because of the chip.

Want to read 99mpg? Reset the trip puter at the top of a mountain then descend the grade without using the fuel pedal and when your close to the bottom of the grade take a puter reading and mpg be up there in no mans world. :)

Why? The fuel is shut off too the engine when the RPM is above idle without the fuel pedal depressed.

Why do some people report extreamly good fuel mileage while other report horrible numbers? You need to compare apples with apples. Alot has to do with the way the truck is driven. With a light foot and 60mph maximum towing speed will yeild better fuel ecomoney than pulling at 70mph with a heavy foot. A truck pulling 16000GCW will get better fuel mileage than one pulling 20000GCW. A 3:73 axle ratio will get more mpg than a 4:10 ratio. The point is to look at the whole ball park just not the number you want to here or see.

Note: Thease are only ball park figures although I did try to gather realestic numbers to work with. Example: my acutal truck cost less T&L

V10 towing 20,000lbs GCW @ 8mpg average using 5k oil changes for 10,000 total miles
Oil and filter= $16eh= $32net
Fuel $1.50gal average= $1875

PSD towing 20,000lbs GCW @ 12mpg average using 5k oil changes for 10,000 total miles
Oil and filter= $32eh= $64net
Fuel $1.50gal average= $1250

100k= PSD total fuel and oil change cost $13,140
100k= V10 total fuel and oil change cost $19,070

Diesel wins by $5930 per 100k miles
My 2K2 diesel cost $3,450 vs V10 $500= $2950 diff

$5930-$2950= $2,980 diesel savings the first 100k miles.

Assuming fuel prices will stay the same (ya right) $1.50gal for 300k miles a PSD saves $14,840 in fuel.

A V-10 cost for the same truck as spec'd below $30,900 or $.103/mile for 300k miles, I already dicounted the up-front cost of the diesel engine.

I paid $30,900 for my PSD truck so my net cost per mile is $30,900-$14,840= $16,060 or $.0535/mile for 300k miles or 1/2 the V10 cost.

Lets take it one step more. Lets say the average price of fuel, gas and diesel, in the next 5yrs averages $2.10/gal, from 5yrs to 10yrs averages $3.10/gal, using 30k total miles/yr at 70% empty and 30% towing 20,000lbs GCW, V10 8mpg towing 14mpg empty, PSD 12mpg towing 20mpg empty, then we get:

V10= empty fuel cost= $39,000 Towing fuel cost= $29,251 or $68,252 gross fuel cost for 10yrs

PSD= empty fuel cost= $27,300 Towing fuel cost= $19,500 or $46,800 gross fuel cost for 10yrs

PSD saves $21,415 in fuel cost over a V10

Have fun in your hunt for the new TV :)

I have not even considered how a PSD will out pull a V10 towing 20,000lbs as to make a V10 last 300k miles one would have to tow at 60% of rated HP RPM.

The diesel wins hands down in cost and towing power no matter how you run the numbers.

T_Bone

I have a '91 460 Ford Gas 4 sp OD (5 sp manual)on a F350 dually flat bed with hay spike. Mine was rebuilt at $29.95 and $500 core.

I repaired mine with common shop tools. He had to come to my house and get my 1 7/8 inch farm wrench and big sledge just to get his apart.

My pump was OEM on a '91 model and the truck had either 175 or 275 k miles. Paid $3500 for the truck and she is a gem. Uses no oil, gets about 10 mpg and is tight.

When I change oil, it is about 5000 or so miles and a $2.69 Motorcraft FL-1A. His filters run about $35 or so and has to do it every 3000.

And then there's the price of diesel. Now on the farm, it's diesel's hands down.
My 2c

Mark

There's way to many variables to take a mileage poll and get any type of usable info even while empty.

First is the nut behind the wheel. This nut has the largest effect of fuel mileage. From my fuel mileage test road, just acellerating slightly to too fast can drop 2mpg in the 5 mile slow drive to my test road where I hold a very steady foot pedal for the testing.

I just made a excell spread sheet for fuel mileage where I track single tank, 3,5,and 10 tank average, trip mileage and life time fuel mileage.

Tank averaging will greatly effect single tank averaging. My consistant 19.2mpg single tank mileage can drop to 18.5mpg with multi-tank averaging

My 15k mile life time fuel mileage is 17.1mpg that included part of 6k miles of pulling 16kGCW thru the Colorado Rockies and the other miles thru the AZ mountains.

My recent 3700 mile 7 State trip was 13.41mpg average. 1300 miles empty at 75mph, 650 miles pulling 15kGCW at 70mph, and 1750 miles pulling 31kGCW at 60mph. Single tank average ran from 7.21mpg to 21.75mpg due too incomplete fillup's and why you need tank averaging.

My new 23k mile life time average is now 15.09mpg, just because of one heavy loaded fast trip.

Life time fuel mileage = total miles / total gallons.

Me, I'm pleased as punch with the above numbers as that's double than I've gotten with any towing vehicle I ever owned in the past 40yrs.

02 F350 CC, DRW, lwb, 4wd, 7.3 PSD, 6spd, 3:73

T_Bone

6 or 7 possibly - but not 15!

Rod

I do have to agree with Mike on Ford, Chevy and Dodge pickups. These trucks should be hitting 30 to 35 mpg on country roads at 50 to 60 mph. I know a guy that bought a new 1 ton Chevy chassis in the 1980s. He installed 18" wheels which gave him equivalant of 3.25 axle gears. His engine was a 6 cylinder Deere 329 turbo diesel. He was a farm equipment dealer and on service calls he got it to 40 mpg. He had over 30 mpg on fifth wheel trailer. Weigth to engine Ford, Chevy and Dodge are using too much cubic inch and too high rpm.

You try your Ford someday with SM on board. It will climb the same hill at same speed turning 1500 rpm as it will at 2500 rpm. Believe me, I put 1/2 million miles on a 6.2 Chevy with 3.24 axle gears and 4 speed. It only turned about 1800 at highway speed and always gave me 30+ mpg.

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You and Rod F have both touched on the major reason the current crop of diesel pickups give the fuel mileage figures they do - Weight to HP ratio. Consider this:

A typical P/U might weigh 5,500# and have 250 HP – that’s about 22 lb per engine HP. On the other hand for an 82,000# tractor trailer with “typical” 450 HP engine it works out around 182 lb/HP. That’s a substantial difference!

NOW if you were to build a pickup with a weight to HP ratio on par with the big rig it would have about 30 HP under the hood (and also a 10 or 13 speed manual transmission). This theortical outfit would probably be capable of 40+ mpg. But it’s unlikely few people would accept the sluggish performance and the constant manual gear changing required.

(Or look at it the other way: The OTR truck would require whopping 3,725 HP engine… ….you’re talking railroad locomotive prime mover here….to equal the weight/HP ratio of the typical diesel pickup. Think THAT outfit would give 15 mpg?!!)

The bottom line is it’s a tradeoff: Performance vs economy. The light truck market has demanded performance over economy, and the car companies have responded.

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Incidentally you are right about the pulling ability of the 250 with a Super M on the flatbed Hugh. It walks it up hills almost as easily 1,500 RPM same it as at 2,500 - only difference is less noise!

I had ocasion several times to have that truck warming up in winter in my yard along with my 6.2 Chevy. Marg. liked to drive the Chevy truck in winter. From the house you could always hear the 6.2 above the Cat on a cold morning. On the road my 6.2 with 3.24 gears was actually a quite pickup. I've watched more guys put 4.10 gears in a pickup, could never figure the purpose other than a noise maker.

Now that truck might have been stuck and just needed a little extra to get it going but it wasn't buried to the axles, no way.

17 to 19 mpg. Best ever drafting behind semi's, empty, mostly highway was a little over 20mpg.

Get about 10 mpg towing my 11.5 foot tall 11,000 pound 5th wheel camper.

18mpg... pretty much anytime..

Steve

casey

1983 Chevy Custom Deluxe 2500 4x4 6.2 diesel auto:
19-25 mpg with 3.42 gears

1991 Dodge Cummins reg. cab 2wd got 21 average,worst I ever got with it was 18 pulling about 8K on the interstate at 70mph..