Actually, it is. I've had a lot of success in creating content using SketchupPro; I even texture the models in Sketchup and after exporting them to .3ds and .im from GMax, everything else shows up. However, you have to use all photo textures in your model. The named colors in Sketchup won't really show up in GMax--it's been my experience anyway.
But, on the topic at hand--good luck with the train cars Jamal!