The problem with this line of thinking is that while it may feel full size in comparison to the Contour, which were miserable failures due to their having little more interior space than the entry Escort, that alone doesn't make it a full size sedan. The market says what it is, and in the market it was comparable to other mid-size sedans.Opinions on something so subjective and relative as size not withstanding, the LS was launched in 1999 as a full size luxury sedan on the same platform and relative size as the full size Jag S type. I vividly recall all the exec hype at that time. Considering it ‘mid-size’ as some do is a relative statement.
Remember, this was first sold during a period when Ford was selling the much smaller Contour/Mystique labeled as mid size. Would you consider them in the same class size? Of course not. They are barely Focus sized. Even the 1999 Taurus was about same or smaller, yet considered full size. And yes, the Town Car was bigger still, but that does not delegate the other’s class, only relative size.
There is nothing subjective about it's size, it was mid-size by every standard of the day.