The latest emulator VHAL is using the AIDL interface so no need for steps 1 and 3 which are changing the previous HIDL VHAL.

Verify that other Test properties exist and if not that means that the build flag is turned off. The flag is ENABLE_VEHICLE_HAL_TEST_PROPERTIES.

If you can detect other test properties, there might be some bug in the implementation.

I would recommend using the VHAL dump commands which will be more helpful. See FakeVehicleHardware::dumpHelp()

https://android.googlesource.com/platform//hardware/interfaces/+/refs/heads/main/automotive/vehicle/aidl/impl/current/fake_impl/hardware/src/FakeVehicleHardware.cpp#1795