Hi ewxlt66,
Yes, the hills CAN be a killer in S.O.C, but here's what I do:
First, you gotta combine trips. Short trips will kill you.
Next, being able to work during any hours of my preference, I start early ... I'm talking being on the road at 4am and home by 2am. No traffic ... easier to NOT offend folks by driving sub 50mph. I drive up trabuco (to Disney) rather than get on the 5fwy where you're expected to do 60mph or better. That way, on side streets, I can pulse & glide ... take it up to 40mph & let it glide down to 30mph. I only hypermile once a year, just to see what I can do for high mileage.
Lastly, you gotta get an EBH (electric block heater) & use it summer & winter. $59 and it'll pay for itself within 3 years. The ebh comes from Toyota & is standard in some parts of canada. The EBH lets you take off with warmer temps so that your 1st 10 minutes of driving don't kill your averages. That's pretty much it. As for hills, you can still get high mpg's by taking them at low speeds ... 35mph & under, but again, being courteous, it's easier if you can hypermile during off hours. I'll be driving "normal" again next week, back on the freeway, but even then, during summer, and anticipating what's ahead, I'll still be pulling down no less than mid 50's.
Good Luck!

Hey, I'm in South OC too...I'm wondering how you do so good on your mileage with how hilly it is...