Not really. It's just a saying that implies very big/very large cars are the result of inferiority complexes, where the buyer tries to compensate his shortcomings by having a huge car.
Usually associated with pipi size, for the laughs, but can also be said about short men.
It could also be a product of Brazil's huge disparity of outcome across the classes... It's almost cultural (and stupid as fuck) that poorer people will drown themselves in debt to buy a car, and, instead of buying popular (and cheaper/functional) models, lots will go the extra "fuck it" and buy stupidly expensive (and larger) cars... they live in precarious conditions, but hey, "I own an expensive car"... it's sad, actually.