Ive seen a lot of "mpg" threads on here, basically "what can I do" and "whats the problem" type questions. Well by accident, and a month long "experiment" Ive found a way for better mpg's. I know this will sound crazy as did I, but so far it has proven correct. I get 15-17 mpg, I had to stop and get mower gas and while I was at it, top off the 3/4 tank I had in the Jeep. Something didnt seem right so I figured the milage and I had got 20 mpg,WTH! So I started topping off anywhere from 1/2 to 3/4 and so far Ive got 19,21, and 20 mpg's! I told you it would sound crazy. For some reason, a full tank runoff only gets me 15-17 mpg. All I can figure is the engine is somehow running more efficient with the extra weight.
I would like to have some volunteers with their daily drivers to try this for a month and report back your results, or offer up some explanations,hope to hear from you all on this, Thanks!
Also, this is a stock 2000 XJ with 135k and auto tranny

it is true that less weight is gonna get you better mileage.

but idk bout 2-3mpg..
im guessing it has more to do with the type of driving your doing

I heard that cars tend to run better if there is more fuel in the tank. Don't know why, but I heard that before.

Any chance you pump has a bad check valve? Does it take a while cranking the engine in the morning to get the engine to start?

I've actually read this elsewhere and have to say, I've noticed that I get better mileage using only the top half of the tank as well (rather than using the whole thing). It makes no sense at all, weight is the enemy of mileage and dragging around 60-120 pounds of liquid should result in poorer fuel economy than dragging around 0-60 pounds... but it doesn't.

Black magic!

You misunderstood, Im getting better milage keeping the tank full than running the tank from full to empty

Common sense tells me the same thing, but its not happening in this case.

Nope, starts first cank,purrs like a I6 should

The only remotely, possible conceivable explanation is that the rip off artists that have us by the ***** selling us this crap, designed there pumps/tanks so when you are not "receiving a full load" less of the undesirable portion is being pumped into the rear of your Jeep. The ethanol/water portion separates.

topping tank off actually adding more than gauge goees like 1/8 to 1/4 more fuel try stopping on full mark every time then check numbers...

Gauge has nothing to do with miles driven divided by gallons used. I filled up, drove 120.1 miles and it took 5.995 gallons to top it off. If the guage didnt work at all, those numbers wouldnt change. I use to always fill up at around 240 miles, which it took a little better than 15 gal. to refill, thats about 16mpg. Yesterday I filled up with a little over 7 gal. at 143 miles, thats right around 20mpg. Like I said, I know it sounds crazy, but the #s dont lie.

what im saying is stop when needle hits full then drve then fill to same spot on gauge it will be more acurate

Hows that different from doing a complete fillup? A complete fillup is easier to obtain than trying to monitor when gauge reads full.

are you filling to exact same spot in tank every time?