i have a flat tire, rear driver side, the spare is a doughnut spare. are they safe to drive on for fifty miles?  my car has awd,it is a 06 impreza.

Is the doughnut spare same height as your tires? Pull spare out and set it next to an inflated tire. Same size height? If so, you can drive on it until you get it fixed. If car is auto and has a FWD fuse holder (dunno if newer cars have one or not) to force FWD, then do that so the rear isn't seeing power.

The emergency spare should work, but male sure its the same size, hopefully you have the stock size tire that that spare was ment to replace.