Diversity Wagon.

[lDestinyl]

 

Mix cargo is a nice setup, but passenger trains like TLK or EC are pulling a wagon like each other. You could do maybe 5 to 10 different versions of the wear and tear of one wagon. The train set would then randomly draw wagon versions and each train would be unique (the number and type of wagons would not change). 

For example.
 

 

[kityatyi]

Luv that wagon! When I still lived back home in Hungary I saw them all the time coming from Bohumín and Praha.