- Follow the previous hints (1, 2, 3) as already recommened (drain your battery fully then recharge, turn off airport etc).
- Leave your laptop plugged in for a while, even after 100% charge (don't know if this step is necessary, but thats what I did).
- Before you unplug your laptop to take on the road, turn the screen brightness all the way down to the last visible level.
- Close the lid and let your laptop go to sleep. (or do it from the Apple menu). Unplug your laptop.
- When you wake your laptop, do not turn up the screen brightness yet. Wait until the battery icon stops "(Calculating...)"
- Wait a few more seconds to let the reported time stabilize.
- Turn up the screen brightness to a comfortable level and work.
Basically the idea is to make the battery calculation occur when the laptop is consuming the least amount of power.

