My '05 has 3.55's and my '86 has 3.73's. I can certainly feel a difference between the two, but I don't think the cost to go to 3.73's from 3.55's is justifiable for that small a difference.

 

No, it's not a joke. I drive my Stang about 10 MPH below the posted freeway speed limit (which is 70) to keep it under 2000 RPMs. I get much better fuel economy this way. I do it with the Crown Vic as well because the gearing on the Vic is even worse (2500+ RPM at 70-80 MPH).

I opted for the $87 factory 3.55s but the only other choice was the stock 3.31s, I wish the GT came with 2.73s. I don't see the benefit to more aggressive gearing for a daily driver.

Since I want better fuel economy from a performance car, I've been looking at the 2008-2009 C6 Corvette w/ 4LT, F55 suspension, and dual-mode mufflers. It gets 27+ MPG on the highway and has better gearing, but also does 0-60 in 4 seconds with 436 hp. In comparison, the Mazda3 and Focus only get 28-32 MPG.

 

To each his own I guess... fuel economy is a complete non-issue to me.

 

go with the 4.10's

 

same here, I didn't buy a mustang for fuel economy

I'm sure you could put in some 2.73 gears, but if you are doing it for fuel economy, it will probably take you quite a while to recover the cost of the gear swap in fuel savings alone.

 

How about a set of Metco Billet pullies?

 

I just swapped out my gears for 3.73's since I needed to replace them anyway and I love the feel. Still quite drivable on the highway but I can feel the extra grunt taking off with just my stock set-up.

 

I'd do the gear swap in my garage, so the cost of the gears and materials would be the only issue ($200+).

Like I said, I just wish Ford offered 2.73s and it certainly would HELP their CAFE numbers if 2.73s were standard. They could then offer 3.55s, 4.10s, and 4.30s as $87-$230 factory options or DIO's. Instead, we have 31 different flavors of ugly body cladding and fake hoodscoops to choose from.