I really like the relaxed, idle feeling when cruising down the highway at 70 or more. I had an '07 Shelby that was great at that, but I felt it could've benefited from 3.55 or so just because 1st gear was so tall it had plenty of clutch action required to make it smooth when pulling away from a light. Anybody know if 1st is just as tall in this GT as the '07 Shelby w/ 3.31?

That's really all I want out of my new GT is a wee bit easier when driving off the line in normal driving, but still retain the relaxed feeling. i.e. having cake and full belly and frosting on your face.

 

I keep the top speed of my Mustang in each gear written in my phone on a note somewhere for just these reasons. Some basic math and I can get the top speeds with the other gears for the most part, but keep in mind I assume 19" wheels and a Manual Transmission. Automatic has different gearing, and the wheels, obviously, would change these numbers too.

3.73s spin the engine at 2112 RPM at 70 MPH.
3.55s spin the engine at 2010 RPM at 70 MPH.

 

see this sticky:
https://themustangsource.com/f726/20...dsheet-483731/

the difference in gear ratio translates directly to RPM at the same speed which pretty much translates directly to MPG at that same speed --

3.31 to 3.73 is roughly 13% difference
3.55 to 3.73 is roughly 5% difference

 

Going with that logic its a little over 1mpg and 100rpm diffrent. I would not even notice that.

 

I test drove the cars with both 3.73 and 3.55 in that order. The 3.73 seemed a bit too much, the 3.55 seemed not quite enough.....so I went with the 3.73!

Couldn't be happier with my choice and I figure that is worth the extra $3 bucks per fill up (that is about all the difference I think it would be).

 

If I wanted real street speed out of a ford I would buy the boss and put 4.56 gears in it or a shelby. I am buying this as a cruiser, some interstate driving some back road, no plans for drag racing or track time. , I already have another a car to play with. I feel that 1900RPM at 60 is not necessary for my application, and 3.55 would do nicely, it has nothing to do with mileage, I expect this 2012 to stay in my family for the next 30yrs along with my '65 & '67. One nice feature about these Mustangs is that you can order them pretty much how you want them. I would really like the 5.4 without having to buy the Shelby, and would be willing to pay a bit more for that option, but not what they are asking

 

OK, here's another question. (I'm still on the fence but I did order the 3.73. I can change that within 1 -2 weeks says the dealer.)

At highway speeds during cruise, let's say 70 mph, is the 3.55 noticeably quieter than the 3.73?

And I am really wondering if the 3.55 is a better DD setup and might actually be easier to hook up consistently for a non-racer.

 

This pretty much sums it up for me too!

 

I do not think the 200 RPM difference at that speed will be any quieter unless you go with aftermarket exhaust that has drone.

I have the GT500 mufflers and they are perfect...the Roush ones might be a bit much depending on your taste.

 

I went with 3.73's for my '11 GT. However, more gear is always better, IMHO. My '07 GT had 4.10's, my '03 Mach 1 had 4.30's, my '93 5.0L had 4.10's, my '89 5.0L had 3.73's, and my '68 GTO had 3.90's. My motto has always been: don't fear the gear!

 

At 70, the 3.73's are at around 2100-2150 rpms.........

 

Not a 2011 but I run a 08 S/C with 3:73. Came from a 3:31. I at first thought hmm..it does not seem a whole lot different...until I had to hit it one time. Yeah....3:73 are great !

 

If you're planning on doing some N/A mods, I recommend the 3.73 or steeper aftermarket ratios. With the heads, cams, and intakes coming out, the rev range keeps extending (sounds like 7800 is the ceiling so far).

I have a stock '11 with 3.73s and hardly use 6th gear. If 4.10's were an option, I would have taken those. I'm used to oldschool stick cars without OD though... In my mind, a 7000 rpm engine turning 3000 or so on the freeway is nothing; these 5.0s can do that and more all day.

When the '11s first came out there was a lot of talk about the best gear for dragstrip times. 3.31s or 3.55s were said to be the ticket... on a factory stock car... truth is, most people interested in dragstrip performance don't leave their cars stock! 3.73s will always pull harder around town too.

Don't fear the gear!

Just thought I would enter the hotrodded Mustang argument into the mix!

 

+1

Took a little bit of time to adjust when I first got the car, but now I couldn't imagine ever using any other ratio...

 

Thanks for all the input. Looks like the increased rpm's with the 3.73 rear are pretty minor at higway speeds unless I am going waaay over the speed limit.

Ordered the 2012 a couple weeks ago and will just stick with my original specs: Ingot Silver w/charcoal int, Premium 400A, Brembo, HIDs & Security, 3.73, Tape delete, Spoiler delete, Stainless billet grille.

 

I really regret not getting 3.73's.

 

Do you have 3.31? I can't imagine there being a huge difference between the two. I'm thinking of going with 3.55 for my order today.

 

I have 3.55's in mine and have no complaints. I've never driven a 3.73 car. Check the spreadsheet that is stickied at the top of this forum (M6 gearing spreadsheet). This will give you all the information you need to know. Test drive both ratios back to back if you need to.

If fuel mileage is a concern, stick with the 3.31's. The best I've gotten is 22 MPG combined. I know it can do better, but I'm not giving it a chance. If I wanted a fuel miser I would have bought a Fiesta.

 

I ended up picking 3.55 for my order today. I've only driven the 3.73's on this and thought it was just barely a bit much. The 3.31 I had on the '07 Shelby were just a bit tall. Figured this should be just right for my daily driver.

 

3.73