A quick and simple method to get rid of the plastic new freight car look is to spray a light coat of Dullcoat.  This will take away the 'toy' train look of your layout.  If you don't have any Testor's Dullcoat you can use any Matte Finish spray to get the same results.  Just a simple spray to each side and let dry.  This can be done to any plastic kits also.

Hopper Weathering Clinic
By Bill Mock
December 2009

Here is the first stages of weathering of my new BN [ ... ]

Scratch building is defined in Wikipedia as “The process of building a scale model "from scratch", ie. from raw materials, rather than building it from [ ... ]