Thanks for all of the input, everyone! My mileage continues to fall (I'm now in dead-last "place"). Toyota has agreed to check out my car more thoroughly to make sure nothing is wrong, but they feel it's probably just the hills...

 

Unfortunately I would have to agree. Like I mentioned in my earlier post, the hills will kill your gas mileage. And if that is most of your driving then there is probably nothing the dealer will be able to do. Sorry . I would suggesting taking it on a long highway drive and see what you get. Take it north on 101 out of SF going towards Santa Rosa and beyond. I'll bet your overall MPG will increase quite a bit...Try it and let us know.