For new manufacturers (makes), add them to https://rock.willowcreek.org/admin/general/defined-types/82.
For new models, add them (with associated manufacturer/make) to https://rock.willowcreek.org/admin/general/defined-types/83.
Search the list of values first to make sure they don't exist already.
Existing convention seems to be to use all CAPS for make and model.
These requests are simple and should be done relatively quickly so that C.A.R.S. can record the vehicle in inventory properly.