Most problems develop with use and age, but some seem to be from the factory. Here is what I've seen with my car;
-Wheel bearing failure. Didn't happen on my last two Mustangs.
-Daytime running light failure.
-Sticking gas guage.
-Unpainted strip on roof.
-Front seatbelt not retracting, seems to have a weak spring.
-Transmission (AOD)sloppiness in 4th gear (clunking).
-Uneven wear on one set of brake pads.
-Lose tie rod.
-Shifter sticking. This is related to wear that occurs with the transmission shift cable. I've had one wear, fray and break before.
One problem that seems absent is wiper motor failure. My last two Mustangs (1988, 1993) saw 4 wiper motor failures. I guess they fixed the problem.
-Rich