no, the demand does not manifest itself spontaneously. people just don't decide to wake up and work twice as hard, there has to be legit economic growth. there is a monetary role. its no coincidence that "healthy" economic growth conforms to healthy monetary growth. this directly addresses your point of people wanting cars but not being able to afford them. this demand could be trivially induced artificially by monetary means, but it would lead to unhealthy inflation

monetary cycles typically manifest over an eighteen month period. i.e. the increase or decrease in Fed policy would impact demand directly likely no less than a year. the only way to dramatically alter this...i.e. to actually get people to wake up and work twice as hard takes drastic currency action.

this is all undergrad economics