Multi-channel recording of sounds in a car using multiple microphones

I’m new to the field. I would like to set up a decent quality (at least 16 bit, 22kHz) multi-channel recording experiment using at least 6 microphones with a budget of ~100-300 bucks to record sounds at various positions in a car (signal leaking between channels to be expected). The mics should be tiny and the wiring flexible and flat. So, my idea is to have 6-12 microphones hooked up to a portable digital recorder, a microcontroller, or a DSP development board capable of handling the data streams (e.g. MCHstreamer kit, https://www.minidsp.com/products/usb-audio-interface/mchstreamer). Note: I’m not trying to build a typical microphone array but I’m interested in simultaneous monitoring of multiple distinct sources.

Does anyone have an idea which setup might be most promising with multiple mics?

Any help much appreciated!