The Jeep and the truck would add an extra dimension ( and probably some product placement revenue for Firaxis as 'Jeep' is a brand name as well as a 'generic' term of course.) The train idea sounds like a lot of extra mouse clicking. By the way if a turn is a year or years it is logical that your troops can at least get from one end of your territory to the other in one turn. Actually they could march it in the real world although Russia would be a long haul. Its the speed of advance in friendly as against hostile territory that should be different. I think this is very well factored in by the current game, any more restrictions on internal movement ie trains would detract from this balance and be somewhat tedious.