Hybrid cars do not have an alternator, and the 12V battery is tiny.
Can the original inverter and 12V battery deal with an amplifier and a subwoofer?
The car is a 2014 is300h

(Norwegian and my search words sucks, so this might be answered many times before, sorry)

 

I did it on my rx450h. I use a class D amplifier with high efficency. It works fine and cold. No problem with my 12v battery.
http://www.focal.com/france/amplific...0-fd-1350.html
It's cheaper in Europe, I found a used one for 120€