If driving it a lot I would go with 3.73's. thats what I have and can burn the tires off through 3 gears with ease.They will give you plenty of pick up and not kill you on the highway

 

How much would gas mileage suffer on an auto going from 3.23 -> 3.73?

 

Highway or city?

 

^ both really...

 

Highway will be a few mpg loss. City might not change. With my 4:10s I get about the same city milage and just horrible highway. But I don't drive the highway much and when I do I take the suv.

 

Exactly

 

i lost about 5 mpg

 

One reason you would lose gas mileage is because lower gears makes the car a lot more fun to "play" with. You will have a heavier right foot.....just because the gas pedal is there to tease you. And guys generally don't do performance modifications like this to save on gas. If you look at the car as a recreational hobby, that gets you here and there, it'll weigh easier on your mind.

 

My car gets me here to there. With alot of fun in-between. Lol. I love my 4.10s.