Car amplifier is not very common as a project, because it is usually difficult to build, and expensive. A small error during assembly will result in power amps are not functioning properly. I suggest that you use the PCB for this amplifier. Even so, this circuit is simple to build, compact, relatively inexpensive, and provide a level of performance that will satisfy most of the needs of your car audio.
Car power amplifier circuit using Output Transistor C5100 / A1908. Power Output About 400W RMS at 8 Ohm. Power Supply need 32V DC Asymmetric, For car application you can adding inverter 12VDC symmetic to 32VDC asymmetric.
R1,R3,R5,R6,R7,R9____1K Ohm 1/2 W
R20,R23_____________10 Ohm 1W
R10,R11_____________3k3 Ohm 1/2W
R13,R14_____________220 Ohm 1W
R16,R17_____________3,3 Ohm 1W
R18,R19_____________0,33 Ohm 5W
C1__________________1uF / 50V
Note :There is NO SHORT CIRCUIT PROTECTION on amplifier circuit. The amp is designed to be used within a subwoofer or other speaker enclosure, so this power amp is matched for car subwoofer amplifier. A short circuit on the output signal will destroy the amplifier.The power dissipated is such that great care is needed with transistor mounting and cooler.