mpg 5.0

[crunchie_frog]

I have 99 awd 5.0 Mountaineer with the center console computer display. I used the mpg calculator on several tanks and it matched the mpg I calculated manually at refills so I was confident it was accurate. I was interested in how the mpg varied at different speeds so I used the mpg calculator on the computer to do this. I travel ~10 miles every morning during the week via a relatively uncrowded section of interstate. I used the cruise control to set different speeds and measured the mpg for the exact same section of interstate. I never touched the brakes during the tests and weather conditions were similar (dry, cool) for all tests. I checked the mpg at each speed 3 different times to get the average mpg at those speeds. The mpgs at each individual speed never varied by more than +/-0.1 mpg. The results are below:

55 mph - 23.7 mpg
60 mph - 22.5 mpg
65 mph - 21.7 mpg
70 mph - 19.7 mpg

I thought some folks might be interested in how they might could expect their mpg to vary at different highway speeds. You can see there is quite a bit of difference between 55 mph and 70 mph, 4 mpg.

Also, these tests were done with 5W-20 oil, and I can say that my last oil change I used 5W-30 oil and I lost ~ 0.5mpg when I retested at some of the speeds. I am pretty sure this is why Ford changed their oil specs years ago to 5W-20 for many of their vehicles, along with the fact the lubrication is the same or better.

I am curious if anyone else has done any similar mpg testing using their center console computer and if you have could you share your results. I would be interested in how the mpg varied at speeds less than 55 mph. I was not comfortable with speeds less than 55 mph on the interstate as there was some traffic. At some speed, the mpg will start to go back down, I think probably around 45-50 mph or so.

 

[bill06447]

Nice. Unfortunately once you take that exit ramp your mpg drops to around 9-11 with stop and go urban driving. I originally thought I must have a leak in the fuel tank until I took my first long highway road trip and discovered the mileage difference these trucks return.

Bill

 

[koda2000]

i'm not all that interested in my MPG (i'm retired and i don't put that many miles on my truck), however i use the center console computer to keep an eye on engine performance. i use Molbil 1 10w30 full synthetic (180K on a '01 2WD EB 5.0 and it doesn't get very cold where i live) and i find the best MPG i get is around 23+ and the worst i've ever gotten is around 14.5. i find with cooler weather and winter formula gas, my current average MPG is 16.3 around town with very limited hwy. i checked my daughter's '00 2WD 5.0 Mountaineer yesterday (same oil, same mileage) and found it also showing 16.3 avr MPG). my other daughter's 5.0 AWD '00 Mountaineer w/165K get's slightly less MPG (extra weight). they might do slightly better with 5W20, but i'm afraid to use oil that thin on high-mile vehicles.

of course, around town MPG is extremely dependent on how much stop-and-go you have to contend with, as when your not moving your MPG = zero which kills your average.

 

[Dave 1955]

If you can get 18-22 with these v8 ex's your doing ok!
I love my ex but I also have a 01 subaru outback with the h6-3.0 and it always gets 22-26 and is faster I think then my 5.0 ex..lol...wifes old car and I'm using it has a dd some and for sure as a winter beater..way too low to the ground though!

 

[crunchie_frog]

i'm not all that interested in my MPG (i'm retired and i don't put that many miles on my truck), however i use the center console computer to keep an eye on engine performance. i use Molbil 1 10w30 full synthetic (180K on a '01 2WD EB 5.0 and it doesn't get very cold where i live) and i find the best MPG i get is around 23+ and the worst i've ever gotten is around 14.5. i find with cooler weather and winter formula gas, my current average MPG is 16.3 around town with very limited hwy. i checked my daughter's '00 2WD 5.0 Mountaineer yesterday (same oil, same mileage) and found it also showing 16.3 avr MPG). my other daughter's 5.0 AWD '00 Mountaineer w/165K get's slightly less MPG (extra weight). they might do slightly better with 5W20, but i'm afraid to use oil that thin on high-mile vehicles.

of course, around town MPG is extremely dependent on how much stop-and-go you have to contend with, as when your not moving your MPG = zero which kills your average.

Thanks Koda for sharing your computer mpg results. I average about 15-17 in my daily driving, which is a mix of stop and go and some interstate. If I really nurse the gas and brakes, I can get ~18.

I was wondering if you know exactly how the computer calculates the mpg? I am guessing it looks at the air flow signal and back calculates fuel usage from that assuming some fuel composition. I guess it also could count the number of times the fuel injectors fire and then uses a certain amount for each firing to get fuel usage. I guess it could also use the gas tank level, but I would not think it would be accurate at all instantaneously, which it seems to be. I was a little surprised at how accurate they seem to be.

 

[koda2000]

Thanks Koda for sharing your computer mpg results. I average about 15-17 in my daily driving, which is a mix of stop and go and some interstate. If I really nurse the gas and brakes, I can get ~18.

I was wondering if you know exactly how the computer calculates the mpg? I am guessing it looks at the air flow signal and back calculates fuel usage from that assuming some fuel composition. I guess it also could count the number of times the fuel injectors fire and then uses a certain amount for each firing to get fuel usage. I guess it could also use the gas tank level, but I would not think it would be accurate at all instantaneously, which it seems to be. I was a little surprised at how accurate they seem to be.

i'm not sure how it calculates MPG, but the fuel level sender in the tank knows how much fuel is in the tank at any given moment and the PCM knows the tank size and how far you driven, so i guess it just does some simple math to figure out how much fuel has been consumed and calculates the average MPG (eg: 300 miles/12 gals = 25 MPG). i also have a Chrysler which has an ECONOMY display setting, which shows you your MPG right now (not as an average).

 

[Dave 1955]

I use a scangauge ll for instant and avg. mpg..works really well.
Has diff trip puters and keeps track of highest temps..rpm's,speed and other things.
Can even adjust for diff size tires.
I move it from the subie to the ex but I might just buy another one.
Even has a performance mode to check diff runs.