Rob
Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
My experience is that I get down around 12-13.5 during the week driving a cold truck 4 miles to work in the morning and 4 miles home in the afternoon. Thankfully I'm moving about 20 miles north next month so it won't wear down my truck so much.
If I'm doing around town driving on a warm engine, I get between 13-14, depending on how heavy my foot is.
Highway between 65-70, I have seen up to 18.5. Towing my fifth wheel 65-70 I see between 9-11.5 depending largely on wind and terrain (it's a tall fifth wheel, wind makes a huge difference.)
Now before anyone jumps all over me, these are mostly overhead readings, which has proven to be within 1/2-1 mpg every time i have checked it. I wouldn't use it to calculate consumption to the Ounce on a cross country trip, but it's accurate enough for me to recognize when something changes.
If I'm doing around town driving on a warm engine, I get between 13-14, depending on how heavy my foot is.
Highway between 65-70, I have seen up to 18.5. Towing my fifth wheel 65-70 I see between 9-11.5 depending largely on wind and terrain (it's a tall fifth wheel, wind makes a huge difference.)
Now before anyone jumps all over me, these are mostly overhead readings, which has proven to be within 1/2-1 mpg every time i have checked it. I wouldn't use it to calculate consumption to the Ounce on a cross country trip, but it's accurate enough for me to recognize when something changes.
Post Fiend
Joined: Feb 2002
Posts: 10,600
Likes: 3
From: Carhenge
I used to get 16.5 to 17.5 mpg with mine when I first bought it about a decade ago.
But after years of reading on this forum about what increased mileage for other guys, and spending thousands of dollars and hundreds of hours on modifications and tuning, I can proudly say that I now consistently get 16.5 to 17.5 mpg.
But after years of reading on this forum about what increased mileage for other guys, and spending thousands of dollars and hundreds of hours on modifications and tuning, I can proudly say that I now consistently get 16.5 to 17.5 mpg.
Senior User
Joined: Feb 2013
Posts: 145
Likes: 0
From: Long Island
I used to get 16.5 to 17.5 mpg with mine when I first bought it about a decade ago.
But after years of reading on this forum about what increased mileage for other guys, and spending thousands of dollars and hundreds of hours on modifications and tuning, I can proudly say that I now consistently get 16.5 to 17.5 mpg.
But after years of reading on this forum about what increased mileage for other guys, and spending thousands of dollars and hundreds of hours on modifications and tuning, I can proudly say that I now consistently get 16.5 to 17.5 mpg.
Pretty much same story for me, get 16-17 most of the time. For a while it tanked when the injectors went out and the HPOP started leaking as well as the fuel bowl, but now that I fixed all of that I'm back to getting decent fuel mileage out of the truck.
If all I do is hop back and forth to work I usually get like 12.5 to 13.5
Laughing Gas
Joined: Nov 2010
Posts: 1,193
Likes: 2
From: D.C. but heart's in TEXAS
It does vary wildly. Most people will say to keep it on cruise control at about 1750 RPM for best efficiency. Driving habits are the main issue, even though we hate to give them that much credence. As someone else mentioned, BOOST LEAKS are a huge MPG killer as well.
I've posted this before, but here goes again...This is a copied post from Dave Whitmer, the MPG guru from *another site.* He gets full credit for this, and his MPG numbers over the years backs all of this up. He gets insane mileage, and while he's done some interesting mods to his truck, he still says driving style is where it's at...read up on "hyper-miling" for some tips. OH...his numbers are without chips / tuners, etc. These are on very basic lightly-or-unmodified trucks.
++++++++++++++
4x4: Big killer of MPG and it forecloses some effective mods. Figure that half-ton of machinery costs you at least 2 MPG vs a 4x2 truck.
Automatic transmission: Another big MPG-killer. It is good for 2 MPG
Dually: It will cost you 1 MPG over a SRW
Crew Cab: It will cost you 0.75 MPG vs a regular cab
Club Cab: It will cost you 0.5 MPG vs a regular cab
Big tires: Anything over 235-85 or 265-75 will hurt. Figure 285s will cost you 1 MPG 305s will cost yet another 1 MPG
Lift: It will cost you 2 MPG
Gearing: Very strong effect on MPG
3.55s will get 1 MPG better than 3.73s (all else equal)
3.73s will get 1 MPG better than 4.10s
My 3.08s (not widely available) improved my economy by 3 MPG over the stock 3.73s
An overdrive (US Gear or Gear Vendor) will improve most trucks by 2-3 MPG
Be very careful about re-gearing if you have an automatic
The 6.4 is somewhat less efficient due to EGR and the filter thingy but I would expect a RC 4x2 six-speed SRW with stock tires and the stock 3.73 gears to get 19-20 MPG if driven normally.
All the stuff above adds up.
A CC 4x4 automatic dually with 305s and a lift and 4.10 gears should expect about 9-10 MPG.
To add insult to injury, the higher MPG truck will probably set you back $10-12,000 less up front. Even with my exotic drivetrain and aero mods, my truck may be one of the ten lowest-cost trucks in The Diesel Stop community.
All these numbers square with my experience and what I have found out talking to literally hundreds of guys plus design engineers.
I've posted this before, but here goes again...This is a copied post from Dave Whitmer, the MPG guru from *another site.* He gets full credit for this, and his MPG numbers over the years backs all of this up. He gets insane mileage, and while he's done some interesting mods to his truck, he still says driving style is where it's at...read up on "hyper-miling" for some tips. OH...his numbers are without chips / tuners, etc. These are on very basic lightly-or-unmodified trucks.
++++++++++++++
4x4: Big killer of MPG and it forecloses some effective mods. Figure that half-ton of machinery costs you at least 2 MPG vs a 4x2 truck.
Automatic transmission: Another big MPG-killer. It is good for 2 MPG
Dually: It will cost you 1 MPG over a SRW
Crew Cab: It will cost you 0.75 MPG vs a regular cab
Club Cab: It will cost you 0.5 MPG vs a regular cab
Big tires: Anything over 235-85 or 265-75 will hurt. Figure 285s will cost you 1 MPG 305s will cost yet another 1 MPG
Lift: It will cost you 2 MPG
Gearing: Very strong effect on MPG
3.55s will get 1 MPG better than 3.73s (all else equal)
3.73s will get 1 MPG better than 4.10s
My 3.08s (not widely available) improved my economy by 3 MPG over the stock 3.73s
An overdrive (US Gear or Gear Vendor) will improve most trucks by 2-3 MPG
Be very careful about re-gearing if you have an automatic
The 6.4 is somewhat less efficient due to EGR and the filter thingy but I would expect a RC 4x2 six-speed SRW with stock tires and the stock 3.73 gears to get 19-20 MPG if driven normally.
All the stuff above adds up.
A CC 4x4 automatic dually with 305s and a lift and 4.10 gears should expect about 9-10 MPG.
To add insult to injury, the higher MPG truck will probably set you back $10-12,000 less up front. Even with my exotic drivetrain and aero mods, my truck may be one of the ten lowest-cost trucks in The Diesel Stop community.
All these numbers square with my experience and what I have found out talking to literally hundreds of guys plus design engineers.
Junior User
Joined: Oct 2012
Posts: 82
Likes: 0
I have a e99 350 4x4 cc long bed srw with 373k on it now. In 99 when I got it with 37,000k I got 15.5.Put a Diablo mid range chip in it three weeks later MPG dropped to 14.5 and has been there every since. No other mods very little maintance besides fluids water pump a couple injectors and front end work and I feel lucky with that.
But I'm putting on 4" exhast rewoking the turbo bellowed up pipes banks cold air intake valve job(needed to pull the heads cause one of the GP's would not come out) new glow plugs EBPV delete. All this work just needed to be done if it gets me better MPG that is an extra added bonus and I think it might but if it dont I still love my truck.
But I'm putting on 4" exhast rewoking the turbo bellowed up pipes banks cold air intake valve job(needed to pull the heads cause one of the GP's would not come out) new glow plugs EBPV delete. All this work just needed to be done if it gets me better MPG that is an extra added bonus and I think it might but if it dont I still love my truck.
Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
It's posts like these that give the overhead it's nickname. Everyone should understand how these computer estimations work... It's a running average since the last reset. If I get up to 80 mph on the top of a hill and coast down the other side and reset the running average, I'd get something close to 100 mpg or better. If I reset the overhead with each fill up and hand calculate each time, I'm consistently between 1/2-1 mpg off one direction or the other.
i ain't rite
Joined: Mar 2005
Posts: 65,448
Likes: 5,517
From: Marlboro Mental Hospital.
mine is always off by at least 35 mpg.
the fuel gauge can be on empty and the lie-o-meter will say i have 350 miles till empty. even though i put 28 gallons in a 29 gallon tank.
the fuel gauge can be on empty and the lie-o-meter will say i have 350 miles till empty. even though i put 28 gallons in a 29 gallon tank.
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Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
Postmaster
Joined: Jun 2010
Posts: 2,555
Likes: 8
From: Longview, TX
Well I know the miles to empty isn't as accurate on mine, but I never pay attention to that anyway. The gravity flow aux tank keeps the bottom tank full, but the miles to empty drops slowly down even though the tank is full. It confuses it pretty bad.
Cargo Master
Joined: Mar 2006
Posts: 2,502
Likes: 2
From: Bend Oregon
speed and driving conditions are the biggest factor in mileage, short trips..stop and go make for crappy MPG, freeway and moderate speeds = 18/19+ on summer blend and 16/17 on winter.
my "record" was hand calculate 34.2 MPG traveling from redding CA to Bend OR. Average temp was aroung 10*F and average speed from Weed CA to Bend OR (200ish miles)was 30 MPH with the Crusie set in 4HI and the roads where packed snow. Total miles of 281 and 8.2 gallons of fuel used. Trip time was over 8 hours and closer to 5 is average.
When I came in to town I thought for sure my fuel gauge was busted ( it was still above 3/4 of a tank) so I stopped to fill up.
my "record" was hand calculate 34.2 MPG traveling from redding CA to Bend OR. Average temp was aroung 10*F and average speed from Weed CA to Bend OR (200ish miles)was 30 MPH with the Crusie set in 4HI and the roads where packed snow. Total miles of 281 and 8.2 gallons of fuel used. Trip time was over 8 hours and closer to 5 is average.
When I came in to town I thought for sure my fuel gauge was busted ( it was still above 3/4 of a tank) so I stopped to fill up.
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