Just some quick tips on the Prius:
1. CC is not as efficient as a smooth foot on the gas pedal.
2. Some energy is lost going to and from battery, so don't try to use battery power alone to accelerate -- it is less efficient in the long run.
3. Boost tire pressure. Try 38f/36r psi, or up to 44/42 if not too harsh.
4. Do not overfill oil. I under fill by 1/4 to 1/3 quart, which really seems to help MPG.
5. A/C does not hurt MPG too much on highway -- more loss when driving slowly.
6. Visit http://john1701a.com for some good info sheets.

I have 126K on my 2004 Prius, with a 48.2 MPG average, and rising.