Right now I have a stock 2007 5.4L F150 Extended Cab 6.5' bed. When I first got it I was thinking "OK if I can get 14MPG stock, hopefully it will only drop to around 10MPG after I do what I want." Well I have been tracking my gas mileage with Fuelly, and I am unhappy to say that I am getting 11.4MPG average, and it seems to go down with every tank of gas. As I have had it for longer, I started driving with more of a lead foot. When I first got it, I drove like an old person, and got 12MPG. As I have had it though, I have started driving it a little harder, taking it to 2300RPMs or so when accelerating. During my last tank of gas, I gunned it maybe 3-5 times, and did 1 short peel, it ended because I took my foot off the gas. Well that tank of gas came to 11.1MPG!

I thought I would first start off with something small like gears or electric fans to help with a little more speed at the wheels, but I have 3.55 gears and am now afraid that if I take it to 4.10s or even 4.30s that it will go down to around 8-9MPG!

Are there any common problems with the 2007s that would cause such terrible gas mileage? Also, its probably like 60-70% city which does not help my cause.

 

Mine is a '07 with a 4.2l and 4.10s... but I got the 5 speed manual. I can tell that my 4.10's have yielded me 22 mpg with street/highway style tires on. Not sure what the stock 3.55's would've done. But I love the extra power with the 4.10s. Especially how it turned my 1st gear into a creeper gear for extra slow traffic or enhanced towing power without killing my left foot and my clutch. I think 4.10's should come stock on any standard vehicle.

 

I think I might just get lower gears and also get a tuner and drop my shift RPMs down to like 1600 or so.

 

when was the last time you changed your air / fuel filters? Do you run cheap gas or do you got o Shell / BP?

Also, what size tires you running? More rubber on the road = more fuel used.

The most notorious reason for bad gas mileage (aside from being a full sized truck with a V8) is the right foot.

 

I got the truck about a month ago, it had 33K miles on it. I do not get cheap gas, I go to shell. I was running 93 Octane when I got the 12MPG, and 87 Octane gets me about the same mileage. My tires and rims are not actually stock, they are the 20" Rims that are options with the 275/55/20 Pirelli Scorpions. As far as air and fuel filters go, I am pretty sure the dealer said they replace them, and I did look at my air filter last week and it was clean.

I have a ton of air and fuel filters for this vehicle, so I guess I can swap them out on my next day off with fresh ones.

 

hey now..i got 21-22 mpg(instant) but for a good stretch at 60mph headed to the ocean this past September with 35x12.50s.........

 

expressway driving vs 70% city driving is a big difference. I somehow doubt 21-22 mpg, my 4.2 only sometimes does 20 expressway.

Also, it is a common and well accepted fact that wider tires = more rubber on the road = more friction = more power needed to get them moving and maintain speed. The tire width being 275 is larger than stock. My city MPG went from 18 to 16 when i put 275/70/17's on.

 

With a mix of highway and city driving I am at a running average of 14 mpg right now and I am ok with that (running 89 oct with gryphon level 2 and 3.73 gears). I do have a heavy foot, if I were capable of: my milage would probably get better.

I think this may be your problem....if you are running larger tires and did not recalibrate your speedodemtor you are atcually going further than it reports therefor your mpg on a tank will calculate out lower than it actually is. If you get a programmer and correct that you may be happy with what you see.

 

Dude its definitly cause of the city... I have the 05 5.4 extended cab w/ shortbed and stock 235 tires and K&N intake and keeping it under 2k If im lucky ill get 300miles to the tank....

Its cause I drive city and there is so much stop lights and stop signs (LA area)..... But if im on the freeway like driving to the Arizona River... On half a tank I get 300miles!!!

Its definitly the stop and go that kills gas....

 

Was the speedometer ever corrected for the oversize tires? If not, that is at least part of your problem.