I know it's probably pointless, but let's do another fuel economy thread.
 

I consistently get 12 mpg with 50/50 highway/town driving. I get worse economy when I drive the truck super easy, I might get better economy driving her moderately hard, and I'll get worse economy pulling out at WOT everywhere but still better than driving easy. I gained 1 mpg from installing an electric fan. I lost 1 mpg when I lifted 3.5" which was unexpected. So far, exhaust and intake modifications including cam/lifters/port and polish have made no mileage difference what so ever, only power differences. I lost ~.5 mpg when I went to 265/65r18 Cooper AT3s vs my 255/65r16 Capitol Precision Trac IIs. I run NGK spark plugs, but I can't remember exactly which ones. I might pull one later to check, I need to check them anyway. My truck has 142k miles, automatic transmission, stock gears. I currently run Rotella 15w40 oil and 85w140 gear oil. I have previously run 15w40 Royal Purple, no mileage change. I have a light brush guard on the front, probably about 50-60lbs. The truck runs the factory 190 stat (short term) and I have a hi-lift mounted on one of the roof rails. I keep probably 400 lbs worth of tools and stuff in the back hatch area and I have a 5 seater truck. I also did an A/C delete, mileage changes were inconclusive. Oh, and all new O2 sensors, but still on the factory MAF (unless it was changed by the PO) and I have a minor pre-O2 exhaust leak, but enough to throw a code. Runs a little rich. To be fixed with headers and all new exhaust because the factory manifold to y-pipe gaskets keep leaking.

As stated, I consistently get 12 mpg whether I am doing town or highway driving, and shockingly whether I am towing or not.

I have heard of guys consistently getting 15, my truck didn't get that when it was all stock. I've also heard a few guys say that they get 17-19 which I find insane, but believable because I somehow got 19 on ONE tank, and I've never been able to replicate it.

So, I'd love to hear from anyone and everyone! Give us a huge info dump on your truck. Lift, plugs, sensor age, mods, tire size, 4.6 vs 4.0, intake, exhaust, etc. Post everything you can think of and what mileage you get, as well as what changed your mileage if you know. I'm not all about hyper-miling, but there's such a large gap between what some people get and what others get that there's got to be a way to squeeze a few more MPGs out of my daily driver.

Thanks guys!

Doing an edit because it was brought to my attention I didn't mention gasoline. I exclusively use Shell 93 octane and my mileage calculations are accounting for the larger tire size. Also I have STI 8mm plug wires.

The one thing you didn't mention is what type fuel you use.

I recently did a 1200 mile trip and noted 15.6 all freeway 75mph half the way and 65 on two lane the rest of the way. On one 300 mile leg of that trip I ran Costco Supreme 92 octane 10% ethanol. 15.6 mpg. On that same leg reverse direction running Chevron supreme zero ethanol and one can seafoam (because the Costco gas gave noticeably weaker response) i got 17.6!!

The 17.6 was also entirely on 200 miles of that leg that were 60mph speed limit two lane highway.

Then on a recent freeway trip, Chevron supreme 10% ethanol, 75mph, back to 15.6 mpg.

My thought is freeway speeds of 75-80 mph which is 2800+ RPM as well as ethanol in the gas could lead to less mpg.

Most of my driving is around town driving. Not much over 40 MPH.

UltraGauge says 9.07 MPG.

Lift: TF MD Springes w/ 2" SLS spacers
Tires: 255/70R18 Hankook DynaPro ATM
4.0 w/ Crower 229 cam
TF Sliders

I also have 85w140 oil in the transfer case and diffs. I am sure the higher viscosity affects MPG in a negative way.

My mpg is super high, I dont know why.
I always use Shell gas.
5W30 con. oil, if I am not mistaken.
It shows around 22mpg on highway if the ac is off and I dont go over 60mph! Everything is stock + a metal brush guard.
it goes as low as 3-4mpg if I 'drag race' from a complete stop.

How are people reading mpg?

Only decent way is to divide number of actual miles travelled, by number of actual gallons it took to get you that far.

Any other electronic wizardry is going to be less accurate and so misleading in any kind of poll/study/thread thingy.

I usually do between 12-12.5.

I have a bluetooth obdII reader and torque app on my phone.
i checked the device on 2 vehicles ( Crossfire and a Rio)by waiting until the gas light comes on, adding 10$ gas and drive it until the light comes back on.
and what i calculated was super close to what it said. So I assumed what it says for dII is going to be correct also. Maybe I should calculate it the old school way to make sure. 22 should be impossible with this machine.

The instrument cluster mileage will be incorrect with tires that are a different size form stock.

You can calibrate the UltraGauge to correct mileage. You need a road with mile markers. You go X miles and compare it to the UltraGauge, then adjust/calibrate the UltraGauge. Then future mileage/MPH reading will be correct. The MPG is close on my UltraGauge based upon the gallons it takes to fill my tank vs. what the UltraGauge says is remaining.

17-19 on the highway 15 mpg around town 87 octane DII

15-17 on the highway 11-12 mpg around town 87 octane 1983 110

I edited to include that I exclusively use Shell 93 octane and my calculations are done using the trip counter divided by gallons and accounted for the larger tires.

What kind of spark plugs and wires are you guys running who are getting 15+?

I might have to try a tank of no ethanol.

Between 15-19 on the highway for all three, depends on which way the wind is coming from. The 4.0 gets a little better in town. RR probably gets the best overall on the highway, but it is also the lightest of the bunch. 89 octane.

Oh, and what's your altitude? Where I live is around 2500 ft above sea level.

Well seems that all of you guys are getting good milage, I'll have to do the hand calculations to make sure the UG is correct but here are the numbers I have calculated by UG:

Altitude - 7200' ASL
City - 10.6
Hwy - 12.2

I use just generic 91 Octane with ethanol from Kings Sooper, I'll try a tank from Shell see if that changes in comparison with a tank from King Sooper. Also does the Sea Foam work as a gas additive?? Never tried it.

Cheers!

Looks like Chicago is 575 feet above sea level. I run standard plug wires and champion copper core plugs

After my next fill up I think I'll switch to the copper plugs and see if that helps much or any. Also gonna try a tank of no ethanol 93 octane, but that will be after I've tried copper plugs for a tank so I can conclusively see which makes what difference, if any.

I averaged about 15.7 on my DashCommand app driving from Syracuse NY to South Jersey... I was running Wawa 92 octane gas from NJ. On the way back, I averaged about 12.6 on 93 octane Sunoco. Considerably lower mileage, but I've since developed a small vacuum leak so I think it's dropping my mileage pretty heavily. Running pretty much stock, with an electric fan added that's about it.

04,,D2,, 4.6 on a 2100 mile trip 4 adults cargo space full ,,
Factory brush guard & sidesteps , AC running whole time, ambiant temp 80 to 100,, 255/55/18 terra Grappler tires, champion platinum spark plugs , 8mm blue wires,,
engine oil Mobil1 0w40, gear/diff oil Mobil1 75w90, Trans fluid Maxlife synthetic Dex/merc,
Average 16.7mpg, doing 75-80 mph, diff premium gas 91-93 depending what was available,(best mpg when adding "Gumout complete fuel system cleaner" to tank)
best when daughter driving 17.8mpg,,worst when son driving 15mpg,
maybe road condition also had something to do with it uphill/downhill , flat,
But she got better mpg because would keep very good constant speed,
In city lots of stop & go average speed 35mph around 10-12mpg or worse ,

The 110 would probably do better if I had overdrive so the RPM wasn't so high. Of course if I had a over drive I would probably drive faster than 55 mph.

I have a stock 04 SE that gets 13-14MPG. I mostly drive in the city. I'm using Castrol GTX 10W-40 and Bosch plugs. I only use Shell VPower 91 octane.

1998 Disco I, get 15-17 mpg. On some long freeway trips, I've gotten up to 18.5 mpg per tankful. Thats dividing the miles by the fuel I put into the tank. But around here general driving, 15mpg.

As I read your post, I'm trying to figure out why you have 400 lbs of tools and parts you are carrying around? That's eating into your mileage. Try getting rid of all your excess weight including the jack and any tall carriers, see what that does. The old MAF might have something to do with it. When I changed the MAF on my Jetta TDI it went from barely running (not throwing codes) to running like new with full power restored. I had cleaned it multiple times with MAF cleaner too and that didn't help. It's worth considering replacing.

Alex I think your trip counter can't be accurate if you have larger tires... Also if your tires are larger that means the circumference of the tire is larger meaning you travel a larger distance than what your counter will measure as a completed turn. Maybe I'm wrong I don't know if you have had things calibrated right. I have stock 03discovery hse7 I don't carry a heavy load I average 15-16 I don't speed crazy nothing over 75. I only use 93octane.

I used the old fashioned way to measure, miles divided by gallons used from previous fill. My Ultragauge reads 5 mph lower than the speedometer at 70mph for what that's worth which is why I don't rely on that for mpg readings.

I should add that I had two adult passengers and had the AC on the whole time i measured.

Stock tire size (90k on Michelins!!!) and blue plug wires, not sure the brand.

Can't really compare — everyone here uses these funny "miles" and "gallons". ;)
Finally got all my O2 sensors done a few weeks back (harder than it looks — nearly impossible to get any wrench sweep on the from driver's). Then drove Ottawa to Toronto. Didn't work out the proper fuel consumption, but did do the fill on leaving - fill on arrival. Worked out to 15¢/km on premium gas at the lowest price in years. Not very scientific, I know.
When I first had her I worked it out at 25¢/km (at a different gas price admittedly).
But at any rate, big difference from doing the O2 sensors. I recommend that to everyone.

I have nowhere else to keep them and still have them available to me since I'm in school and living on campus, and as much as I use them I can't afford to not have them. Plus, with them back there I can help buddies who need it without running back and forth to get tools.

The MAF is definitely on my list, just no $$$ for it right now.

It's not, I account for the size difference in all of my calculations.

Looks like that works out to about 25 cents/mile. Not sure how Canadian gas prices are, but looks like you're paying about 4 cents more/mile than I am.

My DII gets 25mpg and I am not going to think otherwise.

I'm scared I will sell it if I ever check to see how many miles per gallon it really gets.

lol :D


I always just tell myself it's paid for an a car payment is more than the gas

Ok, I went ahead and changed my plugs today from the NGK BPR5ES, which is evidentally already a copper core plug. Anywho, changed anyway to the NGK BPR5EY which is the V-Power copper core plug. Engine seems to run quite a bit smoother with marginally better power and smoother acceleration, but I'm guessing that's mostly from having fresh plugs.

Here are the old plugs. They've got 21k miles on them and they actually look pretty good other than the deposits. Got all the colors; black, white, and red. I found it strange that there was both black AND white deposits. The black is from running a little rich, which I already knew about. I believe the white is caused from the engine (I think, after seeing the plugs) leaning out for a split second near and at WOT around 3k RPM which has been happening for some time. Another reason I plan to replace the MAF soon.

Attachment 56418

I run champion copper cores in pretty much everything butI have had good luck with NGK. They are good plugs.

I'll probably try the Champion plugs after the next 20k since that seems to be about how long copper cores seem to last. I only gained about .5 mpg last time I changed plugs and those had almost definitely been in the truck the first 120k of it's life 'cause they were F*CKED. I'm surprised they were working at all, the insulating ceramics were cracked and the nubs were worn down to nothing.

I got around 15-16mpg when I first got her with stock tires and 97K miles. After larger tires and a lift I noticed right away my mpg dropped to around 12-14. I really noticed the difference when I used to fill up every 330+ miles and now I'm lucky to get 280miles out a tank. I do have 181K miles on my disco's original engine so she's a little tired and some MPG loss is to be expected. Hell I'm kinda like my disco too I guess, I don't get up and move as fast as I used to, and I run out of gas faster these days too.

Will Headers/dual exhaust and a K&N Air filter get better milage? And what about a performance CHIP? Or are they made for Rovers?

Headers/more free flowing exhaust will (I've been told) gain you about 50 miles to a tank. The K&N won't change it. You can't really get a good performance chip for these trucks. Best option there would be to ship your ECU over seas to have it re programmed , but that's really expensive and not worth the investment just for fuel gains.