On the highway I get 48 MPG US at 65 miles per hour - basically level ground, using cruise control and A/C on but it was not hot. Wind will have an effect as well.
I get 45 MPG US at 72 miles per hour. Same conditions as above.

The original posters targets are achievable. My car is also new, BTW. I'm sure the Texas heat has a lot to do with our differences.

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)