I have a question for all those out there with an automatic and 3.23 gears. Since this is an A4 specific thing, I posted it here. What kind of gas mileage have you gotten with 3.23 gears? I used to be able to get 28 mpg on the highway with my 2.73's, but got rid of those a while back. I put in 3.42's, but I do more highway driving now, and since this is and always will be a daily driver/weekend car and never a drag/race car, I would prefer to put in a higher gear. 3.23 doesn't seem like much of a change from 3.42. Considering 3.08 (Yukon sells I believe), but don't know how to program the computer for it afterword. Thanks.

 

25.5mpg at freeway legal speeds,24.5mpg running with traffic on freeway. Data acquired on 8 trips from Ohio to Florida.

Based on your post,you had 2.73s'(2 series carrier) and you now have 3.42s'(3 series carrier OR 2 series carrier with a spacer OR 3.42 'thick' aftermarket gearset. 3.08s' will ONLY work on a 2 series carrier.

 

True. I kept the 2 series carrier and got a 3.42 thick gear. Thanks for the MPG info. 3.23's are most likely not worth my effort, but 3.08's might be.

 

I've accumulated this data over time from posts
for A4
the 3.08 is a guesstimate based on the other data.

2.73-25.9
3.08-24.7
3.23-24.5*
3.42-24.0
3.73-23.0
4.10-22.2
4.56-21.5*

*-my results

 

I was getting 23 mpg highway with my 3.23's.

 

The 3.42s are perfect for me but my milage stinks b/c of an o2 sensor. 70 mph is around 2200 rpms.

 

I got 24 on the highway crusing at 72-73mph the other day on my way to Chicago.

 

i get about 18mpg combined. 60/40 city/hw

 

kind of my thoughts, are you looking at saving money, reduced noise, or ability to drive further
if saving money, you would have to drive a long way/time to recover what you lay out for gear changes
if your not cam'ed to big, you could possible bring in your lockup earlier with the higher (neu.) rear and maybe reclaim some milage

 

Looking to save on fuel consumption more than anything. Engine is completely stock. 3.42's are just not a very highway friendly gear. Love the throttle response, though. If I can manage to get another car for every day, I'll keep this one as is. It was actually louder on the highway with 2.73 gears. Engine rpm was just at the right place at highway speeds to hit the right frequency and create resonance in there that could be really annoying at times.

 

based on your original post of 28mpg with 2.73s,and using 24mpg for 3.42s & 25mpg for 3.08s',every 1000 miles you'd save $6.80 with 3.08 and $24.00 with 2.73 based on a $4.00 per gallon gas cost.

 

What I do not understand, is why did you purchase a performance vehicle if you are concerned with mpg?

Sara (2001 Z28) has 3.73:1 rearend gears, coupled to a 3000 stall 2.5 str, and I get 18mpg freeway, HOWEVER it is a hoot to drive, she runs like a raped ape.