Distinguishing "designs"

The presence of selection within a process does not prevent it from being an intelligent design process. What is important is whether anticipation by someone or something contributing to the process affects the form of the outcome.For example, I could design a face using photofit software. The computer generates alterations to the current image, and I select alterations which best match a form that I know in advance.The term "natural selection" does not exclude intelligent selection or intelligent design.

It is conceivable that adaptive timescales would be reduced because survival capability is being anticipated rather than necessarily being put to the test.Also, with intelligence comes error and 'vogue'. Features that are neutral to survival and would otherwise be merely allowed, may now become preferred. This could lead to the development of apparently useless or part developed features.

I could equally interpret the car and the lawn mower as ecosystems in which the form, 'spark plug', exists.This could be similar to finding a particular bacteria in organisms of different species, or finding a particular bird nesting in various types of shrub.

I took the term "standard part" in the OP as referring to a relationship between functional units.In biological terms a functional unit could be a cell, a unicellular organism, a micro-organism, an organ, a macro-organism, an ecosystem etc. i.e a living construct that has evolved to function in its own right.I would define a "part of a unit" as another unit without which the whole would either not function, or would be functionally impaired.So, with my definition, a bacterium that is necessary for digestion is part of the whole organism or digestive organ, because, without it, the organism or organ could not function. Similarly, elements of an ecosystem are parts of that living system. Removing part of an ecosystem could cause the whole system to fail.This would mean biological "parts" can appear to "borrow from one another". The same bacterium can be found in the gut of different organisms (as the spark plug is found in different mechanical devices). The same bird can be found in different ecosystems, etc.

This particular biological definition of "part", based on structure, has no direct equivalent in a mechanical device. That is why I used a definition based on function. Surely you need a definition that can be applied to both.