They originally motor coach had 64 seats, 32 smoking and 32 non-smoking, and were painted in ordinary SBB green.

Most of the technical equipment is installed below the passenger compartment, leading to a higher than usual floor level than ordinary carriages had.

The conventional transformer technology with its rough step controller (28 running notches) together with occasional heavy vibrations led to the nickname "Schüttelbecher" ("shaker").

This included cloth seats instead of the plastic ones and some other interior modifications, NPZ livery, automatic doors for conductor-less operation as well as the installation of an additional thyristor controller, for which a passenger compartment had to be given up.

The RBe 540 are usually used together with one or more Einheitswagen ("standard coaches") I or II as well as a control car BDt or Bt for commuter service.