Well, this thread sure got a lot of response (not!). What, no enterprising folks out there willing to fiddle? Anyway, I just returned from a 1300 mile round trip. Maybe it was a fluke but I got better mileage than ever before on the freeway, two tanks at ~32.5mpg and one at 31.x. This was mostly at 70-85mph, flat road, with some mountain climbing between CA and ID. I have done this trip the last two weekends and got consistently 28.x MPG each time.
I was a little softer footed this trip... but 32mpg? With 17x8.0 wheels? The best I ever got in the past was 30-31mpg under similar driving conditions, but that was on the skinny stock wheels & tires. The big wheels cut a good 10% off my mileage and I almost never got more than 27-28mpg after mounting them 18 months ago. Now, I advance the injection timing and get noticeably better mileage... hmmm. I wonder what it would do with the stock wheels on there, maybe 33-35mpg!
Or it all could just be a fluke, like I said. I'll be watching my MPG numbers carefully over the next few tanks...
Regards,