Help me see 55 mpg!

[Loren]

I'm doing an "economy run" this weekend. About 200 miles of gas-wasting fun on mostly rural roads in Central Florida.

I'm almost positive I can achieve 55 mpg. I've seen 50 mpg (49.9, actually) already. I do all of the basic "passive" hypermiling tricks, lots of DFCO coasting, anticipating traffic, smooth and gentle acceleration, maintaining momentum as much as possible, a little pulse & glide.

I do have to keep an average speed of 45 mph on this trek (them's the rules of this economy run), which means speeds of up to 55-60 wherever and whenever I can to balance out the areas with lower speed limits. That's going to make it a challenge, but it also makes it a much more realistic test.

The car already has the rear seat removed and a lightweight crankshaft pulley installed. Wheels are fairly light, but tires are very wide. Nothing I can do about that besides air them up more than usual, which I will do.

I'll run the whole trip without the AC, that should gain me 2-3 mpg.

I don't normally cut the ignition at stop lights, but I will for this trip. That's probably worth another 1/2 mpg or so, maybe more.

I was considering taping over the upper grill, half of the lower grill, the foglight holes (I have them punched out for brake ducting for track use) and taping the hood seams all for better aerodynamics. Worth doing?

I've heard higher octane can improve mpg a little. I'll be at about 1/2 tank before Sunday, so I'll have half a tank of 87. I guess it wouldn't hurt to fill up for the run using 91 or 93 octane. Will probably average to about 89 octane.

Any other ideas on how to get that last little bit of MPG without getting too crazy?