Make a single car on every train kid friendly and call it the Kidz Kar or Kiddie Kar.
I suggest dedicating a single car on every train to be kid friendly and call it the Kiddie Kar. You could paint the outside different colors or cartoon characters. The seat cushions could be multi colored and the inside of the car could be colorful with pics of animals, clowns, and other kid friendly things. You could have advertisements for kid friendly things on the walls also. I think it would be great, especially for weekends when you have a lot of families riding. You'd have to start small given the $100K limit, but it would definitely be popular and grow.