Whenever appraoching the subsonic speeds (>0.8 mach), at a great flight level(might be FL360 or more) you will face great amounts of parasite drags which is going to increase your Vmd, but still not SFC at horrible levels. But when at lower, for eg inital approach, there is going to be more TSFC because of drag both caused by intense air and less lift of slower speeds. In this instance, greater N1 might be required, which is going to cause also more fuel flow. But this is a aircraft specific subject. Of course, in a DG-1000 glider, we need no thrust either. All on lift and wing design.