To the OP. While you should brush up on you knowledge I'd bet the reason you asked this question is probably because maybe you were with a friend and you both heard some bass from a ways off and disagreed about what was in the trunk and how much power. Maybe not but who cares anyway, a car with 200 watts and a 10 can be heard. It all depends. The same setup in a different car may not be heard. At the same time though, an old car might only need a hundred watts or so to get a sub moving enough to hear it from a distance.