[i_am_socket]

It depends on the car whether or not you can restart while coasting in neutral. My corolla can restart in neutral at almost any speed (haven't tried > 35 though).

You may want to think about swapping your Cold Air Intake for a Warm Air Intake. It'll kill some power, but might save you some gas. Good part about that is that it's easily reversible.

I second the notion of posting pics of your car in the aero forum. Lots of body kits add a bit too much flair for the air. On the wing: look for the "Flow Illustrator" thread in the aero forum. That'll give you a bit of data to play with so you know if taking it off will help or hinder your efforts. (from pics i've seen of the '00 stang, I'd think it might be better off)

Pump up the tires, take it slow off the line, keep it slow like you've been doing. I'd guess that unless you go pretty far with hypermiling, taking out the performance mods, and adding aero mods you're probably looking at maybe 23-27 mpg. Go all out and you could break 30 (especially with a tranny swap). Still, getting to 25 will be a big difference.

You could try local places like AutoZone and the like for a ScanGauge. I like shopping on the internet because I'm lazy ;-)


*edit* - looked at a pic again, if yours has those side scoops: consider putting some fairings in front of them. They're parachutes.