。。
I couldn't afford a bicycle. Let alone a car.
Literal
I [topic-は] bicycle [object-を] buy margin [subject-が] did-not-exist. Much-less car [dismissive-なんて].
余裕がない ('have no margin, can't afford'). まして ('much less, let alone') introduces a stronger case — if you can't afford X, even less Y. なんて is a colloquial particle expressing dismissal. The second sentence is a fragment, natural in spoken Japanese.