These folks squeezed out 164mpg in a virtually unmodified insight, in what can only be called "incredibly impractical driving".
The Insight Marathon 2006 -- World Record 2,254.4 miles on one tank of fuel - CleanMPG Forums
The original EPA city/highway rating on the 2000 Insight was 61/70, which has been revised to 49/61. I figure if you just jump in it and drive the speed limit, you'll get in the 60's in real world driving.