RMS watts vs peak watts - what actually matters for car speakers?

RMS watts is what actually matters because that's the continuous power your speaker can handle without damage - peak watts are just marketing fluff, a theoretical spike that lasts milliseconds and doesn't tell you anything useful about real-world performance. When you're matching an amp to speakers, always spec to the RMS rating on both sides; if your amp puts out 50 watts RMS and your speaker is rated for 50 watts RMS, you've got a solid match that'll play clean without blowing anything up. Peak wattage is like knowing a car's top speed when you mostly drive in the city - technically true but not what determines whether your system will work reliably.