It means that it has not been built … ? Did you add it to the hikey960_car.mk ?
You should have those lines
PRODUCT_PACKAGES += android.hardware.automotive.vehicle@2.0 \
android.hardware.automotive.vehicle@2.0-service
Check on the OUT directory if you have out/target/product/hikey960/obj/EXECUTABLES/android.hardware.automotive.vehicle@2.0-service_intermediates folder