In that case, and given your interest in fuel economy, I wouldn't take a chance on a set of tires with unknown rolling resistance properties. The difference is sometimes stunning, and it's going to be a long time for that mistake to wear out before you replace them again.Yeah, I'm in no immediate hurry.
Also, stick to the OEM width for the aerodynamic benefit.
Post a "wanted" ad for Enasaves here on the forum -- lots of owners ditch their factory wheels/tires on a regular basis. Be patient, save some money, and keep the known efficiency performance.
My unscientific experience with Enasaves: I stuck a pair of them on the front of my junk Miata, and compared them against 2 other brands of tires I had on hand in a low-speed rolling test. The Enasaves rolled the farthest... by far.