I just filled up today and was very nervous when I had to drive home from Chapel Hill with my tank so empty!
Here are the facts:
digital screen on my Insight: 51.9 MPG
Miles driven: 507.1
Gallons put in (till auto-shutoff): 10.0 gallons
MPG =
50.71 mpg 
look I'm not bragging, I just want to tell you that something is kicking in here.
My Insight and me are starting to "bond".

I definitely feel a relationship with her. Oops - I called it a "her". LOL! I think I'm really starting to appreciate this sweet little car.
Let me tell you what's so amazing about this tank. This past week includes the 4th of July weekend when I had relatives from out of town who I tried my best to entertain.
First thing I did was drive us (3 passengers and driver) around Jamestown and show them the historical sights and attractions. Then I drove us up to Pilot Mountain State Park which includes an ascent up to ~1000 feet. I had to put it in "S" with the a/c running and 4 occupants in that long climb!
Later that evening I took my guests to a 4th of July event that included an outdoor orchestra concert and music during the fireworks display to the 1812 Overture and marches by Sousa! As you can imagine, the traffic getting out of the parking lot and home was horrendous! Then I had 5 days of commuting to work and other miscellaneous trips around town for various errands, etc. This car is returning 50.7 mpg! I admit that I had to floor it a couple of times and I am learning to use the digital screen a lot better now.
I will say that I have bumped tire pressure up to 42 front / 40 rear. I will also say that one of the comments of my guests was that (under normal driving) the Insight is an extremely
quiet car! It's true. The engine is almost silent. The transmission and electric motor add very little noise to the experience. The tires and road noise are the most prominent.
But my guests commented that the Insight was one of the quietest cars they've ridden in (including Cadillacs!).
Just wanted to share my 4th of July Insight experience.
I love this car!