I could see maybe a delay in the amount of time before certain repairs are made, such as a track repair (most carry extra links to do repairs) but a motor shot could do serious damage and knock a tank out for awhile. Since we do not have any tank retrievers, it would be best to set up a time frame for repair to take place over, say 5 min upon receiving the supplies. In this situation, if my engine has been knocked out and not running, then maybe it would be best to cancel the smoking affect after a few minutes, so my position is not given away...
Either way it would be nice to get some higher ups to identify if this is part of the new damage models or not. (Skuzzy, Waffle, anyone??)
BTW, was reported fixed in 2.18 patch 2: "Fixed a bug that caused vehicle resupply to not work correctly."