I want a data source that gives me the number of individual parts in
different types of machinery.  For example, the number of parts in a
car, or the number of parts in a copier.

At best, you might find a site for each piece of equipment, maybe a
BMW site that has all the parts for each model, but you probably would
have to count them yourself, the same for any other site  - your
suggestion of a copier, but which one??  It is an endlesss question.