heres the proof!

that's a two-door impala (maybe model car?) superimposed over the season 3 dvd promo pic. do you have any images of a two-door in context, i.e. a screencap ?

there is the problem of the window bar. sometimes it's there, sometimes it's not. without the bar, link, the car looks like it could be a two-door, but when john moves, link. perhaps the bar rolls down with the back window, so when both windows are open there's no bar, dunno.

Again I say, it's an interesting detail but,what the hell, check the image below....Much more interesting than the IMPALA!