I've had some really good number on my last tank(considering it was mostly city) and lately on my commute. The only thing different besides removing the WAI (which was for about 100 miles) is a spark plug mod found here.http://fueleconomytips.com/index.php...id=31&Itemid=2
I just used the standard NGK plugs regapped at .035 instead of .044 and indexed. These plugs replace the side gapped and index one that were in there. I've got about 350 miles on them. Don't really know how to test this but it sure is not hurting anything and only took about 35 minutes to.
No you drill a 1/16" hole in the bonding strap above the electrode and then dish the electrode a little so that when it fires the spark will go through the hole in the bonding strap for more spark front. There's pictures in the link. It an interesting idea, granted that there is only 2-3% to be gained in this area but every bit helps.
My 2005 Prius mileage had been as high as 61.3 mpg for a tank of gas over the summer. In the past month, my gas mileage dropped to 57.5 mpg, and the Prius, on occasion, wanted to stall when I accelerated or decelerated - although it never actually did.
I bought a set of Autolite platinum spark plugs to see if maybe the plugs are fouling. Can someone tell my what size spark plug socket I need to use to get the spark plugs out?