Welcome to the site, Chad!! You've got a fantastic car to work with.
There is more where those numbers came from but the computer is a tad optimistic -- you'll be able to see the offset after a few tanks.
Your vehicle doesn't have lean burn so the ScanGauge works really well for tracking mileage (as opposed to my lean burn capable first generation Insight where the gauge can't figure out what the fuel consumption actually is). I highly recommend the ScanGauge for conventional vehicle drivers but it will also help you improve your mileage in the Insight by allowing you to track more than the dash can show you.
Just keep your speeds down on the highway and try to avoid stopping whenever you drive! Stay away from the temptation of heavy use of EV mode, too -- it is very inefficient in the Insight because it must turn the engine (without using fuel) as well as move the car. Just use that EV mode for engine off glides without using the battery.
Good luck and enjoy your new car! We look forward to more questions and fantastic results from your new driving efforts.