Suicide Bobb

Recorded gas mileage with mixed city/highway drivin, rounded to the nearest 0.01mpg:
14.55mpg (at 24mph average)

Recorded gas mileage at one constant speed, rounded to the nearest 0.5mpg:
55mph - 30mpg
60mph - 27.5mpg
65mph - 25mpg
70mph - 22.5mpg

Measured speed is accurate within 1mph, and recorded mpg is accurate within +-0.3%

Car is stock besides Pypes mid-mufflers. Passed DEQ (no codes pulled). My reputable mechanic noted absolutely no engine deficiencies, save for a crack in one of the mufflers. Given the easier-breathing exhaust, expect your mpg figures to be slightly less.

danzcool

When I was stock, I averaged around 19MPG, with spirited weekend driving and mostly city otherwise. Supercharged it was around 15.3, now, I get the feeling it won't be quite that good.

UPRSharad

I average between 22.5 and 23 MPG depending on how much I run my A/C. (that's on a stock 4.6/manual trans with a CAI, Exhaust, and UPR 93 octane tune)

marcuskeeler

Booting round town, stop/starting etc, I honestly don't bother monitoring gas useage. I run into Michigan a few times a year from here in Ontario and then it's very easy to check because basically it takes one complete tank to get from my door to Flint. I stick the cruise on at around 70-75mph and I get easy 25mpg.

Interestingly, and thankfully, I didn't see a big jump in consumption when I had the Whipple installed. Despite the added parasidic losses I can barely tell the difference in consumption on the same trip.
If I had to put a number on it I would say something insignificant like 5%.

rdsx18

I used to get 22-23 on the highway when I was stock, but now between the mods and driving harder, I average 17ish.

Suicide Bobb

I don't understand how you guys are getting such higher numbers. I don't drive my car THAT hard, at least not hard enough to warrant a 10mpg difference...I mean, maybe if you guys are like 90% highway miles without ever putting your foot on the floor...

PNYXPRESS

when my 08 comes out of the garage for its occassional trip I will avg around 27-30mpg, but thats 100% highway at 70mph with 3.31 gears and only mod being k&n CAI. Hand calculated per trip.

SmileyOr

I've kept mileage records for years. It wasn't until my last two cars that I compared the trip meter to what I was calculating with my fuel receipts. IN my 2005 Audi Allroad and Acura TL Type S the trip meters were so close I stopped bothering to compare or question them. Technology just keeps getting better.

Now I just need to find the right Mustang for me at the right price

streetzstylz

Mine gets almost 30 straight hwy driving but driving in town like I stole it I get as low as 13

Nunja Business

I have found an interesting phenomenon with my automatic GT/CS Vert.
Slowly accelerating up to speed (55) makes my mileage drop (according to the AVG MPG gauge) but gunning it for a shorter time doesn't.
By that I mean:
It takes me 1/10 of a mile of distance to get up to speed, accelerating smoothly.
It takes me 1/16 of a mile to get up to speed, not flooring it but revving a pretty decent amount.
Surprisingly, the latter technique seems to use less gas overall.
I am getting 22-23 MPG with 80/20 Hwy/City and I am not ginger with my right foot. Clean TB, Seafoam, and never any gas but Chevron/Texaco.