Wondering if any of you Altima Hybrid owners could report on the maintenance you have done, that has helped your car maintain good gas mileage.

The only thing I've done particularly was have the spark plugs replaced around 60k miles.

Is there ANY maintenance to be done to the hybrid battery?

My mileage in California (LA/OC) is significantly worse than most posted here.
When I used to be the primary driver of the car, I averaged 30.5 mpg (mostly town driving) using the best of cautious hybrid driving tips (slow acceleration, lots of coasting, staying in EV mode as long as possible, etc.). My best city tanks could be 32 mpg. Meanwhile, as my wife and kids drive "normally", they average only 27.5 mpg. It's really consistent. (On trips via freeway, I can get over 35).

Lately, I've noticed that on startup, the hybrid battery indicator can be at the very bottom; as if it's not turned on at all. And then after a few seconds, it rises. This is new.
So, I'm wondering if my hybrid battery needs any attention.

We just passed 120,000 miles. I'm taking it to the dealer for an oil change next week. Wondering if I should pursue any other hybrid-specific or general maintenance.

Thanks for any recommendations.

Craig