akdoggie

I get about 25 with the Bullit wheels and stock 235 BFG's. I run a Diablo tune for 91 and usually use my cruise control on the hiway. You'd be surprised how much fuel you can save with it holding a steady speed. It was higher before I did the 373 gear changeout. My last tank with these gears was 23.84 mpg, so my gears have caused a small drop in mpg. I like the power curve I have right now, but I doubt that the SD coil (maybe some from the wires-definitely smoother) makes any difference. I put it on because my daughter bought it and the livewires for Xmas a year ago and so I was sort of forced to put it on. I've had no problems with this car at all.

I'm currently having my CS/GT front fascia painted, then I'll install it. I'm also installing an ambient console (09 Mustang donor), just waiting for factory connectors to attach the front footwell lights. I'm also putting ambient (7 color) LED's into the door pull pockets.

MoneyShot

Ugh... well congrats everyone on your awesome gas mileage. Looks more and more like the problem is me. I haven't had a chance to check my tire pressure yet, I will try this afternoon.

@Siber Express congrats to you especially. Never heard of a 4.0 getting mileage that high. I have run a whole tank on the interstate on stock rubber and got just under 27. Did anything change to the 4.0 in 2010? You say "before my tune" So this was on the stock tune? what about after?

I know i need an alignment and I'm running stock auto tranny fluid at 85K but I wouldn't think that would account for any MPG loss, <1 MPG I would think.

Thank you all for your replies!

Nuke

Wait, you have fuel mileage issues and you haven't checked your tire pressure but DID do a ton of other expensive maintenance? Weird...

Have you checked to see if your brakes are dragging? Bad wheel bearing? Alignment issues? Any of those will attribute to rolling resistance. Air intake clear?...

Siber Express

With the tune it was doing about the same and as far as I know the 2010 4.0 was the same.
Mileage went up over 2 MPG just changing the muffler right when I first got it.
I wish my 13 got the mileage the 10 got, but it is about a mile per gallon under what the average was on it

MoneyShot

So,
New struts & shocks,
New strut mounts,
New LCAs,
Two Alignments,
Fresh Autolite plugs,
AM 93 tune,

Last tank of gas...

15 MGP

Its 90% city but that is still too low. I guess this is the new norm

Stang-aholic

try re setting the gas pedal calibration.

Nuke

The 4.0 is as much a pig in city driving as the 4.6 is. My wife is a bit of a lead foot and her '06 4.0 only gets about 15-18 MPG with mostly city driving. So, it's somewhat of the OLD norm.

Stang-aholic

Btw I get 17.1mpg (80% city driving) in mine, but its got a lot of gas suking mods lol

Nuke

Heck, just "MY COLOR" alone will rob you of 1-2 MPG... LOL!

JayBeStangs94

I would get about 18 on my 07 v6 pp with cai, 91 tune, and 18 inch gt wheels off a 2011.

On my 2013, Highway ive averaged at 24, and city between 17 and 19, with 19 inch wheels. Can't really complain tho for what you're getting out of it