Ultragauge displays instantaneous consumption, gallons per hour and average consumption. There are also a total of 78 possible gauges. A few are listed below, and their possible uses
__coolant temperature - useful to let you know if the car is ready for high load driving, i.e. at optimal temperature
__LOD, IGN, and MAP - if you know how to read these, you can find when your Civic is cruising in i-vtec, and when it isn't
__TPS - it is also useful to find if your car is in i-vtec mode.
i-vtec is just one possible use of these gauges; they will also help during pulse and glide, along with other hypermiling techniques.