If you're really concerned about gas milage you might want to think about a V6 also. I have found some pretty good deals for the S197 4.0, and just recently i purchased one of my own. It is an '07 4.0, had 65,000 miles on it and i paid $6800. The 4.0 SOHC has pretty good pep to it and gets good mpg for a Mustang. Over the past couple months i'd say i averaged 24-25 mpg combined (city and hwy) while still having some fun with it.

Just some food for you're though. And yes I realize there's still nothing quite like a V8 Stang