Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for four-door
The base price for that four-door machine: $57,400, which is roughly the price of a BMW 535.A123 Goes Chapter 11
October 19, 2012
A four-door sedan, and it was a dark color, and he left there like a crazy bunch of hoodlums.Warren Commission (10 of 26): Hearings Vol. X (of 15)
The President's Commission on the Assassination of President Kennedy
Yes, sir; this is the 1961 Lincoln Continental four-door convertible bubbletop.
This is a 1956 Cadillac, four-door touring car with the top down.