Ford Powerstroke Diesel Forum banner

How to get maximum gas mileage?

19K views 74 replies 37 participants last post by  john galt 
#1 · (Edited)
I have a 2002 f 350 7.3 Crew cab With 200,000 miles On it.

I drive about 1000 miles per week and carry about 300 pounds equipment. 1/3 of my driving is at 70 miles per hour, 1/3 is at 65 miles per hour and 1/3 is about 55 miles. 95 percent of the time I'm on cruise control.

So my concern is not about power but maximum gas mileage.

I heard I could get almost 25 mpg. Does anyone here know if that can be done, and if so, how?
 
#2 ·
You will never see 25, probably not even 20 mpg. Start with an intake, straight 4" exhaust, and a chip from a place like DP or PHP and get an economy tune along with others, check tire pressures, any boost leaks, make the truck as light as possible, drive like a grandpa, keep the RPM's below 2,000 and don't use the cruise control and you might see 19 highway.
 
  • Like
Reactions: msinklair
#5 · (Edited)
The reason I asked is because some fellow told me his son has a '99 7.3 with a Crew Cab and gets 25 mpg. Wasn't sure if it was a steaming pile he was handing me so I came here. I figured the best possible would probably be 19 mpg.

I have a K&N filter. Think I'll try an intake and see how that does. I use highway tires at 75 psi, drive like a grampa and keep the truck as light as possible.

When I was a builder I carried at least a thousand pounds all the time, and fuel wasn't much of a concern. But now that the construction industry is dead, I do work that requires lots of driving. I don't want to give up the reliability this truck has given me for the last 10 years, so was just asking for ways to improve the mileage.

Sounds like the only thing left to do is intake, exhaust, and a chip with some tunings.
 
#6 ·
It is not a dually. It has a 27" Knaack saddle box on the back and a 16' truck rack. Other than that I have kept her bone stock since I intend to get 600K out of this thing or I want my money back. I've treated her like a baby from day 1 when I drove her off the dealer's lot with 10 miles on her.
 
#7 ·
The mods I listed will not shorten the life expectancy of the truck at all, just help it to breath better and get a little bit of performance out of it.
 
#9 ·
Factory exhaust with muffler? Did it come with a CAT?
4.10s or higher?
I've done 45 mph for most of a day moving a buddy around and it came out to 22 I think hand calculated.
 
#15 ·
If you want better MPG, don't do 70... Do 55-60 and you'll get more - but, it'll take awhile to get there!

I did 67-69 (tee hee 69) from Nashville to Atl and got just over 21. I don't know if 25 is truly possible - especially with the rack on top. Major wind resistance!


From iPhone forum junkie
 
#18 ·
Man, I hate when people call people ''lairs''......YOU truly DONT know their conditions, atmospheric pressure, altitude, winds aloft, speeds, grades, temps, driving styles, fuels, mods, Must I go ON and ON 01crewcab7.3 and anyone else that wants to fight. If he said he got 11-28 or even 30 MPG he got it. Unless you drive His truck and document your findings and when you do, IF they Dont match what he says, come back on this forum and talk.

Now for the lighter side, my 6.0L 2003, got an Easy 21 MPG....want me to list why(I wont I'll keep you guessing)??
My E99 7.3L gets 18-19 MPG and thats going fairly easy. But I also use a Special blend of fuels(and I will Not tell what I use,..Hint I'm a Lead Aircraft Tech), drive all special like, live where its cold, at an easy altitude, with min. grades, and little stop and go traffic. Does someone want to prove me wrong with my MPG like the other forum members that so nicely spoke up? Have a Good Day!
 
#20 ·
I was not starting a fight, just simply stating that I do not believe 28 miles per gallon to be true from these trucks. Especially with a truck as heavy, and aerodynamic as his. There is a guy on I forget what forum, that has a heavily modified 7.3 powerstroke that gets 27. He has tons of aerodynamic mods, super high gears etc etc. I just know that I have seen tons of people use the over head console and think they are getting extremely good fuel mileage which is not the case, as well as people hand calculating their mileage incorrectly and claiming to get numbers that just aren't accurate. Whether or not he got 28, you're right I was not there and do not know for sure, but with a truck such as his, or even mine, I do not think it likely to be true. Just my opinion.
 
#19 · (Edited)
Call me out on it if you want but I've gotten 25(hand calculated) going 60-65 all day long and being easy on the pedal. I have noticed that 62mph is the sweet spot. So if you can afford to go a little slower on your commutes you will see much better mileage. Also having a 4x4 will kill you mileage....Alot of extra weight.
 
#25 ·
When I got mine and it was completely stock I got 16.5 on trip from St.Louis running I55 at 75mph. Since I have done a few mods I have gotten 15-15.5 but this has been local stop and go driving. I'm interested to see how it does when back on the highway. It's hard to keep that right foot out of it since I got that chip...man what a difference...not even the same truck.
 
#26 ·
The best I have ever seen is 23.7 hand calculated; and I'm 2wd. That was the 2am leg of a cross country trip. Filled up south of Kansas City and drove to Bloomington Il via I-70 and I-55. Cruise set at 62mph (I don't see well at night). I wish I could get 28 all day long everyday. Unfortunately my mixed driving yields me a pretty consistent ~17.2 from tank to tank.

After that it was light out again, and over the next 500 miles of my trip I got a hair under 19mpg @ 70mph. Also had to sit in Chicago traffic for some of that tank though.
 
#33 ·
Those numbers are very close to what I get at similar speeds.

Maybe y'all are too much in a hurry and won't slow down to the optimum cruise speeds where I see such great numbers! ;)

I'll be doing over 2700 highway miles over Christmas and will be keeping track of my numbers. If you can be patient, I'll report what I get in a few weeks (and the average speeds I got them at).

We'll probably have the cruise set on 65mph day and night as the best compromise between time and fuel economy. I expect to achieve approximately 22mpg at that speed, burning 124 gallons over the trip at an estimated average price of $4/gallon costing me $496.

If I averaged 70mph and dropped down to 18mpg (maybe 19, but I like to run pessimistic calculations) I'd burn 151gals costing me $604. The trip would be only 3 hours shorter but $108 more expensive! That extra speed translates to $36 for each hour saved; not worth it!

As much as I'd like to get to my destionation sooner I think I'll slow down just that little bit.

BTW, based on past experience I expect the trip to take 50 hours including all stops. We don't stop to sleep. My wife is an experienced long distance driver who regularly drove our old motorhome and has probably logged 2000 miles in the truck pulling our 5th wheel trailer. So I'll sleep while she drives and vice-versa. I'm better at night driving than she is, and she is better at dawn and dusk. In the day it is a toss-up.
 
#27 ·
I curious with the one or two other members that said why are you getting such low mileage...14ish is low. But I am with 01CrewCab7.3, I'll trade my truck for your 28 MPG's, any day of the week, hehe.

Just something to throw out there......Diesels run at the peak efficiency around 1600-1800 RPM's, Play around with those RPM ranges for a few weeks and you'll see what your truck runs better at(mileage wise). Cause it all depends on mods and the truck. My truck runs the best MPG at 1800 even, so since I have a 6 speed, I choose my speed and gears per RPM efficiency. And I have had a personel best of 23ish on straight diesel. If I didnt have stupid 35in tires it'd be better I think, thats going to change soon tho.

And I'm Sorry for my first post that labeled out a few members,......I was a little rascal this morning. ;0
 
#28 ·
Really quick, I see alot of post that say I get this MPG per this speed, It helps if you say the speed and RPM, It gives people a better since of the mileage.
 
#29 ·
Tires also make a moderate change in economy. My truck bone stock with stock size tires averaged 19.0MPG @ 70mph. Now with 305/70R16 M/T's, new single shots, tuning, exhaust, intake, etc. I averaged 18-18.5MPG.

Keep in mind my truck is a 6-spd, and I baby it 95% of the time.

But maintenance and upkeep will be the biggest factor in retaining fuel mileage.
 
#34 ·
I use my chip's economy setting and drive 65 mph at about 1900 RMP never any faster. I do not use the cruise control, I do not accelerate fast, my tires are inflated to 60 pounds, fresh alignment, truck is empty but itself, 30 gallons of fuel and my butt in the seat. Even with the 6 speed I still have seen a best of 16 at 55 mph, at 65, 13-14. Oh well I still love the truck none the less, gets better mileage than my last truck and can out haul it any day.
 
#36 ·
I haven't done these upgrades to my 99 crew cab yet but when I had a 93 F-350 crew cab 4x4 with a 5.8 gas motor I went from a 9 mpg avg. to 13 mpg avg. by doing the following:
Changed the stock belt-driven fan and shroud to a pair of electric fans & custom shroud, changed the fluid in both axles and the T-case to synthetic, and went through the brake system to make sure everything was working, releasing, & adjusted properly.
Just for the record I usually get 20-21mpg with my 99 crew cab 4x4 6-speed, and it is BONE STOCK with 235K on the clock.
 
#37 ·
i got 20mpg 1 time on the I-50. i was doing 55mpg (there was road work so had to slow down) checked over 3/4 of a tank of D2. the rest of the time -18mpg going +73mph. both times i used cruse control and only had 3 people in there and less than 1000lbs in bed.
i run 285-75-16 tires with the super chip in tow safe hand calculated.
slow down and keep steady rpm not so much speed.

if you can get 28mpg that would be doing great.
most of the time i get -17mpg
 
#48 ·
01 Oct 2010 to 15 Dec 2011 miles = 15076
Fuel Gallons: 1115.017 ($4,193.97)
Mile per gallon: 13.5208700853888

Manually calculated with spreadsheet from pump receipts.
Checked in truck with scan gauge II.

2001 F250 mostly stock
That's the same way I'm doing it. I just recently got the truck and only have 1918 miles of data so far, but have seen some points of improvement.

The first 966 (all local) miles I averaged 12.62 MPG

I then adjusted my tire pressure from 50-55psi to 65psi at the same time started using Power Service Diesel Fuel Sup + Cetane Boost for the cold weather.

The next 952 (all local) miles I averaged 13.875

At the last tank fill (not in the calcs yet) I adjusted the tire pressure to 69psi. I already see an improvement in MPG on the "Lie O Meter" I'm using that as "indicator only"
 
#44 ·
Sounds like you're doing great. I think that if you actually took a running average instead of snapshots that you would find your mpg is actually much much lower. For example, don't take mpg for a particular trip but record fuel consumption over a 5000 mile oil change interval and see what you really get. Those little snapshots are very deceiving and very eay to rig.

Sure, there are excuses, but if you really want to know the mpg then you need to eliminate variables such as % fill, tailwind, warm up time, load, etc. that you can only do by accurate measurement over time.

I can get 20 mpg on a one day freeway tank. If I look at my logs honestly then my overall average is mid teens. Nobody is getting 28 mpg repeatedly with a powerstroke in a superduty truck unless they are manipulating the data on purpose or not. Time to face facts.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top