I have no idea what I'm doing right with my truck. You guys have to verify my gas mileage calculation. The two things I'm assuming here that need to verified is:

1)Half a tank shown on the gas guage is truly half a tank. When I hit "E" it tanks my truck 80L or 21gal. to fill. For every 1/4, I use 20L. I know the only way to be sure, is to fill up and see exactly how many litres or gal it take to fill, and I have once at 1/2 taking 40L, and once at 3/4 taking 60L.

2)My speedometer/tripometer adjustment for the increase in tire diameter/circumference. My original tire size was 245/75/r16, and the present tire size is 285/75/r16. The difference is 0.927 or 10%.

After 1/2 tank, my tripometer shows 230km=144miles. Assuming half a tank is 40L or 11gal, I'm getting 14.9mpg in the city! And my last trip on the highway calculated out to be 17.9mpg, even by using the exact number of litres used after fill! I just can't believe these numbers. Is anybody else getting around this also? I must by buying some good quality fuel lately. I'd also like to mention, I've still been driving fairly hard, hitting WOT a bunch of times.

 

That is about average or maybe a little better for the 5.4L, I wouldn't know exactly, I have a 4.6L and get around 15-17 City depending upon my foot and stop and go traffic. But, I get about 18-20 on the highway depeding on the terrain.

 

The F-150 5.4L 4x4 in 1997/8 was only rated for like 13/15mpg, and I use to be getting 12's city and 14's highway with the smaller tires. It makes me want to pick up a performance exhaust to see if I can improve it even more! Anybody else getting these numbers?

 

I am @ 370 miles @ 23-24 gals some times better some
I do beleive it is the gas I use to.

 

hey fordification, do this, fill up the tank, reset trip meter, wait until low fuel light comes on, then fill up again this time noting how many gallons it took to fill up. divide trip miles by the number of gallons used to fill up and you'll get more accurate results. The reason I said this because I get about 165 miles at 1/2 tank mark, but when the low fuel light comes on, I only drove about 249 miles and took 21 gallons to fill it back up. in other words, If I base my mileage using consumption at half tank, I am getting about 15 mpg, but if I use the whole tank, I am getting 11.9 mpg which I do believe is more accurate. try it and please post your results. I am finally accepting the fact that I am only gonna get this type of mileage considering my mods and running 15.72 e.t. 1/4 mile at the track. regardless, I feel the fun I experience outweights the fuel inefficiency of my truck. My .02

 

I'm guessing that the longer we can go without resetting the computer, the better mileage these rigs get. I've not reset mine for quite some time now. I think since I last changed plugs. About 6k miles ago. Dunno, I seem to be getting better mileage too. I only calculate at fill up, which is usually at the 1/4 tank mark and I am putting in 18-20 gallons each time and getting 290-300 miles. A number of times, I've waited until the light comes on and then it's only like 21-22 gal. But I'm now getting 15 mpg average. Still, mostly highway, but that's what I say the rig gets now. Still sucks on the wallet (~$200/month), but I'm driving my F150 and I love it!!

 

Newbie, it's not quite and of the tank when the low fuel like comes on, which explains why your only getting 249miles and not 330miles on a tank, which is really quite high! I now have 410km, with a little less then a 1/4 tank left. I should easily be able to hit my calculated mark of 460km(230x2) before it hits "E", which would give me 15mpg. If I do, and it takes no more then 80L's to fill, my calculations will be correct.

MitchF150, your getting fairly similiar numbers that I'm getting. Maybe a little better.

 

The best I have ever been able to get was a 400 mile round trip done in the same day. When I filled up at 296 miles, it only took 17.7 gals. for a 16.7 mpg run. I just got back from another highway run and went 328 miles and 20.1 gal. for a 16.3 mpg run.

Now this was a pretty mellow run. No WOT romps and probably averaged between 60-70 mph the whole way. Cruise RPM's were right at 1900-1950.

 

The tank before this one, I went 508km=317miles, used 67L=17.7Gal. which=17.9mpg on a highway trip from the mountains. This is by far the best I've ever gotten. I'd also like to point out that sometimes if you under fill and use that number of gallons of fuel it takes to fill in order to calculate the mpg on the previous tank, you get a great number, except when you calculate your next tank it's horrible. Except in my situation, I've had two great consecutive fuel mileage gains, which I'd say over rights the chance of an inaccurate calculation. I try to be skeptical when I see such a huge gain.

 

For those interested, here is a link to my fuel chart. I keep it updated as often as I can. Usually every fillup. My truck is a 2001 XLT SuperCab Flareside 4x2, w/ 5.4 and 3.55 rearend, stock 275/60/17 BFG RLT tires. Only engine mod is a K&N air filter.

http://members.home.net/deep6blue/fuel/fuel.htm

 

You gotta use the formula Newbie goes by. Start with your trip odometer on 0, then run it down. Next fill up, divide miles driven by the gallons used to fill up (or in your case, kilometer divided by liters). Remember that the guage is only accurate two times on any tank full: When its full and when its empty!

 

Yep, my estimate was very close. I actually travelled 469km, and it only took 78L, with the guage showing a needle width left. So it's safe to say 1/2 tank is 1/2 a tank. 469km+10%(tire size difference)=516km=322.5miles/20.608gal.(87oct.)=[bddddddddddr]15.6mpg!! It seems to be only getting better! This was like 90%city driving and 10%highway, with the odd WOT burst. I just can't believe it. It can't be my calculations because I haven't changed anything since the first day I purchased it. Use to be getting like high 11's low 12's.

deep6blue, you seem to be getting about what I'm getting. There should be more of a difference between 4x2 and 4x4's I would think. Do you factor in your tire size difference from stock, or is your speedo recalibrated?

 

fordificaton,

I think you are correct that our gages actually show the correct amount of gas in the tank. I've got the bigger tank, and consistently get about 100 miles per quarter, as an average. If it's highway driving I can do a lot better.

Sven