The Rover 400 can be divided into two different models. The first is very very similar to the Rover 200 Mark 2, but has a longer back end. This we call the Mark 2, just to confuse people, because there was no mark1!! These vehicles were produced between 1990 and 1995.
The Mark 3 is the smaller rounder looking car, which is generally more modern in style, and was available from 1995 onwards.