The new, low-emission Tier IV Diesels need to be made. They could be used on numerous routes. Possible engines: -GE GEVO Hybrid Prototype (w/ flashing charging lights and included test car) [This engine would be awesome!] -GE ET44AC (UP, CSX, CN, NS) -GE ET44C4 (BNSF) -EMD SD70ACe-T4 (BNSF, UP, Prototype #1501) These engines could also come with some modern rolling stock in different liveries. I also think that these models should all be sold as a package, not individually.
