Ahh, yes, that is a bit on the large side. You need to (1) open a .blender file containing an existing 'bus; (2) save that file with a new name; (3) import your model into a different layer than the existing 'bus; (5) resize it (hotkey "s" then type a proportion, such as 0.01) to be approximately in the right sort of scale; and (6) adjust the size more precisely until it is in scale with the existing 'bus. Once that is done, you can then render and export the images.