hawkeye18

It's not so much about miles per gallon, it's more about smiles per gallon.

I saw that somewhere. It's not mine.

Anyway, the 3.73s will be most of that. Ford got the mileage numbers on a 3.31 equipped car, and going with a higher gear ratio will lower the mileage a commensurate amount.

Additionally, for best mileage you best not go much faster than about 60... 65 tops. The Mustang has the aerodynamics of a barn, and much faster than 60 drag starts playing a much bigger factor in economy. I will lose 3mpg just by cruising at 75 instead of 60. It's up to you whether it's worth it.

E_cox310

This is exactly why i stopped caring about MPG because not only is it boring to cruise at 60, it's also impossible on the California freeways, lol. MPG shouldn't be on a mustang owners mind because you can't enjoy it if you want the best MPG...fact

DocSnickers

Speaking of aerodynamics of barn lets not forget you can't see the right side of the car most of the time. Can't count the amount of times I have cut it to close turning into a parking lot and whacked the passenger tires over a curb drives me freaking nuts. It's always when I have to turn to cut in sharp to go past another car.

2012mustang

have had no problem getting 19 city 26-28 on long hauls stock 3.31 gears roush 575 sc

jthorn9

Well during normal driving, around town with some highway my GT and V6 both average around the same at 18-22 mpg. Now on long highway cruises the V6 does win by a land slide. The GT will get 24-26 mpg, the V6 really does get 30 mpg. Catch is, the drive must be consistent (very little accelerating/slowing/turning), basically a near constant speed, for a couple hours on in, then and only then will you see those peak numbers. Like I said, around town though, both cars average about them same.

kawasakiguy

It would be amazing to get that 26mpg considering my last f body got almost that. But even with my 3.31 rear end this thing still revs too high on the highway to achieve that. Maybe after break in it will get better....?

Norm Peterson

Just how close to 100% highway are your 23 mpg experiences? How flat was the terrain?

I make a very specific 325-ish mile trip often enough that the mpg for the route I used to take would very reliably produce 23 mpg, plus/minus a small fraction. After I traded away about 11.5 miles of surface street driving with traffic lights and traffic for about 20 more miles of Interstate driving, I've been at or above 25 mpg. No cruise control use at all; traffic in the Northeast does not reasonably permit this in many areas even if I was willing to use it, which I'm not.

Your "city" mpg is about the same as what I get with my 4.6L. That suggests that we're using about the same amount of power most of the time under these driving conditions. You just have a whole lot more tucked away in reserve.


Norm

Bullitt2059

Just wanted to comment my experience with my 08 with the 3.73 gearing (granted, not a 5.0) . the car is rated at 15city/23highway, and i was lucky to get 22 highway cruising at 65-70 before. I recently had it tuned, and on a 93 race tune, I managed 28mpg cruising at about 72mph over the course of almost a full tank (roughly 275 miles). The tune really seemed to improve fuel economy, if I can keep my foot off of it.

Andy13186

worst mpg 15
best mpg about 18 for me, decent amount of WOT every tank

old mustang had about the same, my old 99 maxima got 17-19 mpg

im sure on a 100% highway 6th gear 65-70 mph cruise i could go 24 mpg or more

BrazenStang

MPG is all about perspective. I'll let any one of you drive my Bronco w/ 351W for a week and have you fill it up. After that bit of "perspective" you will kill to get your 18-19 MPG Mustang back. lol. My Mustang is my econobox!

I get 18 MPG most weeks. On highway I get 22-23 MPG. I am content with those numbers. I don't try to get best MPG, but I think those are pretty solid numbers.