Paths displayed by mongod.exe do not show the drive letter in dbpath or the journaling path unless it is specified by the user on the command line or in a config file, and the actual drive used is dependent on the current working directory when mongod.exe is invoked. On systems on which there are multiple drives (partitions) and where there is a \data\db directory on more than one drive, it isn't clear which one is being used without some poking around.

It would be better to convert path specifications, including default ones, to fully qualified paths complete with drive letter internally and to always display the fully qualified path.