[j12piprius]

Here's a summary of the up/down 125 mile route.

33.7 mpg --> before ultragauge / 67-8 mph
43.9 mpg (41.8 / 46.0) --> ultragauge / P&Dfco / 58.5 mph
49.6 mpg (48.3 / 51.1) --> grill blocks / P&Dfco out / P&Eoc back / 55.8 mph
52.9 mpg (55.9 / 49.9) --> wheel covers / P&Dfco all the way / 48 psi / 53-4 mph

I'm still finding P&D to be just as good as P& engine on coasting in neutral. My car coasts well in gear and there isn't much drag from the engine compared to being in neutral. Thus I usually alternate coasting in gear or neutral, depending on feel, and don't notice a significant change in the average either way. Sometimes one is slightly better, and visa versa.

Eoc would theororetically raise the average by 1.5 mpg, but that didn't work out on the previous return trip and I've decided not to do it anymore. This time I left the key on all the way both directions. The biggest difference is caused by the air resistance and the wind.

The last outward (up) trip at 55.9 mpg was quite encouraging, as the return trip had always been better. However, this time there was a headwind all the way back, the only reason I'm aware of for the 6 mpg drop. My speed has been dropping each trip, which has probably had a significant effect on the mileage. Ironically, I'm so focused on mpg now that the speed seems no different than before, when I was entirely focused on speed.