In Death of a Salesman, what does Willy Loman mean when he says, "Don't leave the hubcaps, boys. Get the chamois to the hubcaps."

Willy Loman, failed travelling salesman, arrives home
exhausted from a truncated sales trip. Also at home is his wife, Linda, and his two
sons, Biff and Happy, reunited after the former's lengthy self-imposed exile in the
western U.S. In their bedroom, Biff and Happy listen, offended, as their father talks to
himself in the kitchen below about events of the past. Then a remarkable shift in the
timeline takes place. The playwright transports the audience to
Willy Loman's memory, giving it substance and narrative voice: It is an
idyllic time. Willy, basking in the glow of doting sons and a loving wife, has just
returned home from a fabulously lucrative sales trip. He instructs his boys to polish
his car until it gleams: "Don't leave the hubcaps. Get the chamois [soft cloth] to the
hubcaps." In the time shift, the car represents both Willy's profession - he drives a
car for a living -, and his quest for the dream of affluence. But especially in his
boys' ritual polishing, it represents the family of the self-made man and his valiant
sons. However, Willy's car has a symbolic polarity. At one pole, located in Willy's time
shift, it represents success, but in the present it represents failure and loss of
control. Later in Act 1, Willy cries to Biff and Happy: "For Christ's sake, I couldn't
get past Yonkers today! Where are you guys, where are you? The woods are burning! I
can't drive a car!"