Prius Noob Here

Smooth steady 70 mph should yield 52 to 53 mpg per BobWilson's chart. Your stop and go should be better than that, say in the 60's if you are careful. If you can slow to 65 mph you'd expect 56 mpg. It looks linear to 65 mpg at 50 mph.

Press up the tire psi to the extent you are comfortable, and enjoy passing by the gas stations!

 

I can't remember how hilly that drive is, but I commute from Denver to Colorado Springs over Monument Pass every day, 50 miles one way. I use no hypermile techniques, drive 75 most of the way and the heater or air conditioner is on EVERY day (the nature of weather on the Front Range). I get a consistent 45 MPG in what I consider to be one of the worse routes I've ever seen for mileage.

 

And that's in a GenII! The GenIII should get even better mileage, should the OP decide to go that route.

 

If you get a USED 2004-2007 Prius with a CARPOOL sticker, you can go single person in the Carpool lane until Jan 1, 2011. That will save a lot of time if you use freeways with Carpool lanes. The 85,000 stickers given out ended about Jan 2007 and go WITH the CAR. Try Craigslist or autotrader.

 

But the 2010 Prius is quicker..bigger engine, better MPG.

 

And I forgot to mention I'm running Bridgestone all season tires (and NOT Low Rolling Resistance tires) so that accounts for a couple MPG anyway.