Is the drag on a high speed trains mainly inertial or skin (parasitic) or is it pretty even? I would expect it to be mainly inertial since it's moving at such a

Is the drag on a high speed trains mainly inertial or skin (parasitic) or is it pretty even? I would expect it to be mainly inertial since it's moving at such a fast speed. If that's the case, isn't there a lot of different techniques to reduce drag actively and dynamically that they can explore instead of drawing vacuum?