Wow. 350, 450, 550 instantaneous mpg! I'm amazed. My car does similar to Who's; The best I've seen on the Cavalier is 180mpg @ 70mph, neutral coast. The Cav burns 0.4 gph at 0 TPS, regardless of rpm: 600 rpm idle, 1100 neutral coast or 2400 coasting in gear.
Edit: Ok, now I'm not amazed. You guys have sticks, while Who and I have automatics. I suspect the SG is taking the rpm into consideration in addition to the injector pulse width. If Who and I could actually get our engines to idle while coasting, we would probably see those high numbers too. Stupid automatics.
P.S. What did the snail say when it hitched a ride on the turtle?
Weeeeee!