What do the cars symbolize in F. Scott Fitzgerald's The Great Gatsby?

"rich cream color, bright with nickel, swollen here and there in its monstrous length with triumphant hat-boxes and supper-boxes and tool-boxes, and terraced with a labyrinth of wind-shields that mirrored a dozen suns. sitting down behind many layers of glass in a sort of green leather conservatory..."

it stands out. its very shiny because of the nickel. its cream with a greenish interior.