Dont know about Roco but Marklin have cheap plastic interiors of whatever colour is available from who ever makes them. I paint interiors as a green or red etc floor and seats are not what I would want from a coach costing around 60/90 pounds. Mike our Swiis expert should be able to give you the correct colurs.

The best known decor of the SBB coaches was green upholstery in the non-smoking section and red upholstery in the smoking section. The first class coaches had white headrest covers.
I think that some of the earlier coaches had brown upholstery in second class.

Later, different materials were applied to the seats depending on what the railroad had decided was their standard upholstery at that moment.
https://www.bahnbilder.d...ast.html#google_vignette

https://www.bahnbilder.d...-35.html#google_vignette

https://www.bahnbilder.d.../a-ew-2-nl-noch-mit.html

Regards

Mike C

I forgot to go over the computer numbering. A handful of EWII B may have been delivered with the original SBB + CFF/SBB + FFS and B XXXX markings, but the lion's share were delivered with the UIC markings already included as the production models were delivered starting 1965.

https://www.lokifahrer.c...-2.htm#Einheitswagen-III

https://de.wikipedia.org...en_(Schweiz,_Normalspur)

The final (SBB) EWII coach was delivered in 1975.

Starting around 1983, coaches received the <+> SBB CFF FFS markings during revisions.
A few years later, further modifications resulted in coaches receiving the so-called "Comfortwagen" label with the added turquoise stripe.
Many of the EWIIAB were repainted to match the new NPZ trainsets which went into service in the mid-1980s.

Still later, a number of the EWII coaches were repainted in the "Papagei" livery for the "Regio" trains.

Regards

Mike C