Anyone take out their 4.10's to put in either 3.73, or stocks?

I need gas mileage, I am only getting 200-220 miles per tank now. I am looking to get back my 300-350 miles per tank i had with my stock gears. My job requires that I put over 100 miles a day almost just for work, which is 500 miles a week, with my driving another 150 miles. I am ripping through gas. Anyone put their stock gears back in? If anyone has any more info for me please let me know. Thanks

My boss actually *logged* better gas milage with 4.10's than his stock gear.
I thought it odd, but I would still figure the difference would only be minimal. At least with M6's...A4's might be a different story?

Why not just get a cheap dailly driver. Toyota or Honda comes to mind.