i have 3.08 gears in my car currently and average 19--20mpg. if i go with 3.73's, what kind of change should i expect from those who have done this already?
i do about 65% street and the rest is higway mainly around 60-70mph average.
It all depends on how heavy your right foot is but could be about 1-2 mpg less. At highway speed you will be about 2-300 more rpm with the 3.73's. No one goes to lower gears looking for better MPG.
city driving should see an increase but you will lose hwy mpg. 3.73s arent that tall of a gear. not sure on the rest of your combo but I would think 15-city and 22-24 hwy if everything is in good working order.
Me personally i feel the difference is minimal, not enough to worry about from the gears themselves.
Your driving is going to be the real problem, 3.08 to 3.73 multiplies the fun factor, your lack of restraint is going to cost you quite a bit of gas and you will be going through rear tires twice as fast.