Why would they give that RMS wattage if cars run at 12.5-13.5 volts?
I was looking at the Alpine MRD-M1005 and they boast 1000 RMS at 2 ohms. However if you read the fine print, that rating is at 14.4 Volts. The amp only puts out 700 RMS at 12V. The Actual output of this amp is between 700-950 RMS based on what your car puts out for voltage...
Lot of manufacturers use the "dynamic" numbers to inflate the power ratings. As you can see, 1114w sounds a lot better than 700w. It's all about bending/hiding the truth to sell more products. If you notice, Sony always uses peak power numbers for just about everything. Their so called 1000w amp is really 200w, and that's pushing it too.
that amplifier uses an unregulated power supply so it's a fixed duty cycle, and power output varies with voltage input. car batteries are 12VDC, and so is the charging system at idle. above idle, the voltage rises to 13.8-14.4VDC though, so the power output will increase when you're running the car above idle, provided the alternator has enough current to power the amplifier adequately.