I didn't think you had the S/C? :dunno:

I don't have S/C I have nitrous. I have Dinan stage 3 engine and transmission software.

I always thought the stage 3 was the S/C, not that it really matters, it's just an arbitrary number that Dinan assigns.

on my '05 4.4i with a well maintained engine/tranny (as I'm sure most of you have as well), I get 531miles to a tank when cruising at 65mph. I've done that a bunch of times and its funny cause I NEVER thought I'd be able to get that. And thats not math from the RANGE either, its legit begin to end of trip mileage.
This is also in winter when gas gets sucked back more, BUT I run 255/55R18's too, so it kinda evens out I guess.

I checked my Dinan receipts. I have stage 4 engine and transmission software that matches up with Dinan other mods other than the S/C. There is engine software that comes with the supercharger but there is no stage associated. Stage 4 is to match up with Dinan throttle body, air flow meter, cold air box and exhaust.

'03 4.4 sport pkg here. I have done several runs between Dallas TX and Spring Hill FL (1100 miles, GPS verified) with a SINGLE fuel stop and showing 60 miles to empty at arrival. New fluids in trans/Xfer case/diffs (at 100k miles), tires inflated to 38 psi (I usually remove the staggered wheels and mount the "highway wheels" for long road trips, those are 255-55-18s non-stagger), no AC, windows up and speeds below 70mph. That works out to around 580 miles a tank. I've logged and calculated my mileage and regularly see over 23 MPG during highway driving when I can keep it under 70 MPH. Running at 75 MPH the mileage drops to around 20 MPG.

FWIW, I add 10 oz of Lucas Upper Cylinder Lube with each fill up, an addition $3 on a $90 fill is not noticeable. I've been using this product for over 20 yrs and have yet to have a fuel system issue on any of my vehicles.

Regular city driving in the Dallas area returns around 400 miles per tank (just now checked the OBC, 345 traveled with 53 to E)

Great! I see that our vehicles with the proper maintenance and care will yield great MPG. But FYI the vehicles are set with the speedometer/odometer to that vehicle configuration, ie engine, transmition, diff, tire size, to get the most accurate mileage, meaning changing the size of the tire to a smaller one will spin faster telling the vehicle is going more miles than it ussually goes, so in the long run it will say an innacurate reading. Somewhere on the net, there's a tire/speed calculator that will tell you what is your actual speed, which in the long run will affect the odometer reading, just look into it.

Well aware of tire diameter, the V speed rated 255-55-18s are the OE wheels that came on my truck and are the wheels I mentioned on the 580 miles per tank trip. My staggered setup is actually SLIGHTLY larger in diameter then the OE wheels resulting in several fewer revs per mile, this would actually show a lower OBC MPG then actual MPG if the OBC was calibrated perfectly. I GPS log and calculate MPG on long trips, this is more accurate then the OBC data.

Yep...Orlando to Deerfield Beach & back on ONE TANK (410 miles) in my 4.8is. Best gas mileage of any vehicle I ever owned - including a straight 6 Jeep Grand Cherokee.

I guess I was spoiled getting 22-23 MPG (and 300 lb./ft. of torque) from my 2007 335i before I traded it in on my 4.8is. The first few fillups have been a little painful, but worth it for the extra cargo room (the reason for the trade). I'm averaging about 14-15 MPG with mostly city driving. Looking forward to seeing what I can get on my first long road trip (most likely to Grandma's house).