OK, I'm back after two distinct legs.
First leg:
Over Chinook pass to the lower valley, sea level to 5430 and back down. Rain in the mountains. Speeds from 60 down to 35.
149 miles, 5.47 gallons, 27.24 MPG
Second leg: Interstate 82 and Interstate 90
Moderate winds
Speeds right at 66 by cruise control. Did some 71 till I got wise.
471 miles, 18.05 gallons, 26.09 MPG. Speed Kills.........economy
truck configuration:
No bellypan. It had been removed for some maintenance and I ran out of time.
No diffiuser. The tail was absolutely open on the bottom.
No grill block on the first leg. DOH! I left it home, and put some cardboard in at the next stop.
Plusses: I did not drop any parts off. The lights worked. The plastic kept the rain off the cardboard.
Minuses: The plastic came loose over large parts of the critical area between 10% and 30%. I think that billowing plastic caused some problems.
The plastic at the cab/shell joint stretched up, also tripping some things.
The sides of the tail are atrocious! I had no time to really address that. Plastic was starting to tear there.
I think I had the incidence too steep to start with, especially considering the less than ideal surface condition. If I had time I could have peeled off the plastic today, no more rain. I was a little concerned it had some structural benefit in some areas, and the leading lip of cardboard looked very vulnerable to peel back without it.