I never liked the silhouette styled windows on many of the passenger cars, and have thought about replacing them with clear inserts, window shades, and adding some seating, figures and redoing the interior lighting (like overhead LED strips). Obviously the result would be a compromise from a scale perspective due to the thick carbodies and the interior roof mounts, but I think at a glance such modifications might be really effective into tricking the eye to at least suggesting to peer inside the windows rather than present the 2D silhouettes of people.
Has anyone performed any upgrades to their passenger car interiors? I would love to see some examples if you have pictures!