When I first back out of the driveway when the car is cold I sometimes (when the window is open) hear a brief noise coming from the back of the car before braking. The sound is a low-pitch squeak. Maybe the brakes? The car is a 2014 Forte Koup EX with 8,000 miles.
Rust buildup on the rotor surfaces.This is normal if the vehicule was not driven for a while.
+1 My 2010 Forte has done the same. The rust is wiped off after a couple stops.
If the sound is heard before applying the brakes at all, unlikely to be a slight coating of rust on the rotors. The pads don’t touch the rotors until you press on the brakes. In that case I’d guess it is more likely something squeaky in the rear suspension system or something loose in the trunk. Maybe remove everything from the trunk including spare tire and jack if so equipped. If that wasn’t it, next time you take it to the shop ask them to check the rear suspensions bushings. What you are hearing may be normal; the bushings are sometimes made with a polyurethane material , a sort of plastic that could squeak if rub against something metal, esp when cold. When parked you might be able to push down on the rear corners and get it to squeak that way.
I should add my Corolla does the same thing. I’ve never bothered to figure it out, but I did check the rear suspension bushings a few months ago when I was doing some rear brake work, and they were still appearing good.
I have heard that some cars do a self test on first startup after sitting overnight and it make a noise. I don’t remember what system is self testing but it is harmless.
A 2014 Kia with only 8000 miles, going to have to go with rust on rotors.