best i ever got was 22.5 with my 04 heritage with a K&N intake. did it consistantly 3 tanks in a row filling when it got down around a half tank. driving same routes stock gave me 18.9, and with K&N drop in was 19.9. now my 08 has the intake on it and im seeing about 16 average with 87 perf tune and intake....but heavy foot. the intake from my 04 is now on my 08 and the drop-in from my 04 is now in my brother's 03 4.2L

lol got 2 speeding tickets with my 08 and never had any tickets from the 7 vehicles i had before it....78 f150 351W, 86 chevy C-10 305ci, 89 firebird 2.8L, 96 trans am 5.7L, 97 ranger 2.3L(8 spark plugs), 90 5th avenue 3.3L, 04 f150 heritage 4.2L(got pulled over but got warning)...lol

 

Thanks , ive also heard premium fuel is better . Since i drive 75miles one way to work ,i'll have to try a couple of tanks since i'm only getting around 300mi. per tank or should i say fill up .

 

Premium fuel has NOTHING to do with fuel mileage.The main difference between regular, mid-grade and premium gas is the octane rating, which is a measure of gasoline’s resistance to combustion. It’s commonly sold in 87, 89 and 93 grades; 91 or 92 are available in some areas. Certain engines (especially ones with a supercharger or turbocharger) need the high octane go-go juice to prevent engine pinging or knocking, which can be harmful to an engine.

 

You may get slightly better gas mileage on premium, but your end cost in $$$ is going to be higher. Not worth it. I've tried it, and it's maybe 0.5 mpg better.

 

I can get ~8-10 rwhp better on premium by advancing the timing but the only time I've ever run 93 I haven't seen any MPG gains.

Per my last fill up, I just pulled into my driveway with 274 miles on the trip meter and the gas gauge pegged at 1/2 tank. Hoping to break at least 530 miles this tank. 30/70 driving on Wal-Mart E10 with two logged fire responses (***** to the wall).

 

yup. in PA its usually 87, 89, 91, 93. in CO its usually 85, 87, 89, and 91. i run 87 because it has a huge power gain over 85 with my custom tune from vmp. justin told me to use 87 if i notice a difference between the two. 85 just feels very sluggish.

 

Your probably right and Ive done a lot of reading on the topic . Lots of pros and cons - depending on person or blog , forum etc .... But i did see a big difference on my mpg. went from 300 to 350 and a significant powergain on Shells mid-grade - last night topped off tank with Mobile Premium , we'll see how that goes and report back soon .

 

I'm excited. Just finished running down to as low as I'm comfortable without being stuck on the side of the road:



With corrections due to tires, that's 513.7 miles. Even if I did use all 25 gallon, that's 20.5 mpg. Calculating to 24 gallons probable, that's 21.4 mpg. I'm curious as to how far I could squeeze out of it. I might throw a 5-gal can in the bed and start heading to town to top off and get an accurate burn number.

Either way,

Stats: 60% highway, 40% city. Five recorded Code-3 responses. Wal-Mart E-10, 87-octane.

 

and youre the one who said that my 04 heritage didnt get 22.5 like i said...lol. see? it is possible...and mine was made for highway more than yours is...anyways im just messing with you since youre getting close to what i got.

 

What are you referring to, gears?

 

Man! What do you guys do to get 20+ mpg?? I drive about 400 miles a week( work, and small errands around town)...and the best I get Is 16 hwy and like 10 city!! Maybe because i drive a lil too fast?...

 

Probably. If you try to keep it under 2000 rpm you will get much better mileage - and when the IMRC opens around 3000 or so, it will really suck the fuel down.

What mods do you have, which transmission, and what axle ratio? 2wd or 4x4?

 

I see this everywhere. Am I the only 4.2L that opens @ 2500rpm?

And yes, don't go over 2,000 rpm when accelerating. That was my #1 rule to get that tank. IN 5th gear w/ 3.55 non-LS, 70mph nets me 2400rpm so my IMRCs don't open. So anything under 70 will net me 20+ mpg conservatively.

 

I was guessing 3000.

 

Mine has the standard automatic tranny(4 speed w/ overdrive)..the only mod I have is a K&N filter, I have a cherry bomb glasspack but I'm still debating whether to put it on or not. And it's a 2WD