I agree with Yak that owning a hybrid has made me more active in the driving process to maximize fuel efficiency. However, I'm no hypermiler but as I drive the Insight more I've picked up on techniques that will bring out the car's potential in increasing mpg.

Since getting my Insight, I only fill up when near empty to get a better idea of how much gas I used. And with each gas recipt I will write down avegae mpg for that tank and total distance driven, plus any notes that might explain increase or decrease in mpg. I mainly use my car to commute to work and much of my driving is in the city with numerous lights and involves stops and deceleration/acceleration typical of city driving. From my computer reading, I average ~53mpg on each fill-up. My calculations of dividing miles driven by gallons consumed pretty matches the computer reading. Keep in mind this is only city driving. When I do take the freeway, it bumps my mpg average higher. My fill-up ended with an avergae of 55.4mpg. But when I did the calculations, the car's computer seemed 1.7mpg higher. I don't know if that had anything to do with the insanely high freeway mpg I got that bumped the avergae up.

Anyhow, about the Prius. I've read that the Prius can achieve 50-60 mpg. But it seems people I've taked to say they only get mid to high 40s.