[CHOMAT]

Here there is matter to think that the principle of economy can't be a satisfying explanation= the longer the noun( affixation), the shorter the adjective. The chosen examples are obvious.
Some searcher believed that -ic adjectives were chosen according to the essential link between noun and adjective:
Electric shock :the shock is no more than electricity .Here, the adjective is almost a noun
versus
electrical equipment or component : these things deal with electricity but are not essentially electricity it is peripheral.
PerhapsThe electric car instance points out the fuzzy extent of the essential link noun and adjective .

There must be other determining factors weighing on the choice between pairs:
electric car :the phonological factor : euphony electrical car*[l]/ [ka:] idem shock or current which take the stress upon the first syllable
yet electrical components : [l][k] but components takes the stress on the second syllable . prosody ? e'lec/tri /kal/ com'po/nents ? E'lec/tric com'ponents Are the two stresses too close ?
Electric company : 'company most of the time shortened into Electric co

Semantic or/and phonological factors?
We could try on a larger corpus of pairs since the diachronic key should be abandoned.
Alain