With Signature deliveries of one's and two's and three's outside of California, it may not be economical for Tesla to use rail to some geographies. However, it seems that having all the Production X reservation holders configure and being able to batch and ship carloads via rail to various state terminals would achieve economies of scale. Rail can't directly deliver to a Design or Service center, there has to be a Auto Rail Terminal -- Lorton Va (northern VA), West Chicago (Chicago area), Dacula, Ga (Atlanta) a few that I am familiar. From these, they use Truck Carriers -- that is how traditional dealers get their inventory. Using this method, high numbers to a single location (at least a train car load from the factory) has to be the model, since they don't transfer cars to and from rail cars. As Tesla ramps Fremont to nearly 2000 vehicles a week, rail batching most likely will be the transport for S and X. Batching both models via rail to a distant terminal.