8-pin device found in unknown_car_mcm. Looks to be BJT based and very analog-looking. Tentative identification is Analog Devices AD22100.

Reasoning:

• Googling “22100 opamp”, since it was originally thought to be an op-amp, brings up the AD22100 as the first result
• The AD22100 is available in 3- and 8-pin versions. The die has 3 bonded pads and 8 pads total.
• The die is labeled 1992. The AD22100 datasheet references a patent issued in 1991.

Markings (left side near sensing resistor). No vendor logo, just a year, a part number, and (possibly) designer initials.

22100
APB
JP
JB
AB
1992