Hi i work at citroen dealer, and would have to say that the saxo is the most reliable of the current range the most common part to go is the stepper motor which sends the revs all the place when it fails, it costs about £80 for the part. Just check for the usual ware and tear, brakes can be a bit weak and being the 1.0 i dont think it will have power steering so can be heavy on parking even though its a small car.Also check the front seat runners silde back and forth as these can jam.She would be better trying to get a cheap saxo 1.1 desire, you get electric front windows, power steering,cd player body colour bumpers and better seat trim hope that helps.