I like Quicksilver/LeMans' idea about driving a beater to work.
Corporate America is full of people who judge on the superficial. Better to let them feel bad for you than to blow your next promo/raise because you out-classed your boss.
That said, if I worked in Corporate America anymore, I'd probably say f**k it and roll up in the ///M anyway.
Come to think of it, that's probably why I don't