Originally Posted by lawnmore

I would like to explore the other end of this idea. My window sticker shows 20 city- 28 highway. This is a joke. The best I have been able to do is 18 city 23 highway. OK I can live with the city. Currently I am seeing 3000 rpm at 72 mph, way more than necessary to cruise down the highway.
I would like to see a 5 to 7 hundred rpm drop. The engine is very happy between 2200and 2500 rpm so why not gear for that in 6th at highway speed? No doubt the mileage would approach the advertised 28 mpg. The car has 3.88's, what about 3.45's or what ever it takes to get the rpm's down at 70-75 cruising speed to a reasonable 22-25 hundred rpm? Would this really hurt 1st - 4th? Would this take away to much acceleration feel? I realize it's a close ratio gear box, so maybe the answer is in the box and not the final drive ratio. I don't know the solution so I am open for everyones ideas on this.