Ok - here is the current wagon setup for the Suwex flirt (top picture). You can see colour-coded wagons, and the colour-coded wheels show which wagons have bogies and which do not (for example the "C" wagon has no bogies).
I propose making one new wagon - "D new" which replaces the "D" wagon so you would end up with the second picture (bottom).
I realise that the real 6-car Flirt only has pantographs at one end, but that is much more complex to do because it would involve scripting changes in the engines and wagons too. The quickest, simplest approach is a new "D" wagon with doors in, no pantograph, no toilet. I think if I make this, then the community can paint the train for how they want it?