Bulb documentation has always been vague with Nissan documents, and I never figured out why. I hate having to pull stuff apart and reassemble prior to ordering parts and making LED bulbs.
As for 8W, just like your ordinary household bulbs you can get different ratings for them. However, don't get bulbs whose ratings exceed the original. We don't know if the socket can handle higher wattage, nor would the wires support higher current.
Anyhow, with my LED bulbs, here's the estimated wattage:
License Plate - 1W
Trunk Light - 4W
Map Light - 1.2W (using 350mA BuckToot driver)
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