Not on a Mustang but on my gfs sisters 01+ sunfire. Just changed her front brakes (pads & rotors) and took it out for a test drive and about 10 mins into it there was smoke coming out from her wheelwells. I did wipe the rotors with a paper towel before install. This was my first full brake job you could say, but I think I did it right. is the smoke part of the break in? It wasn't smoking that bad but enough to notice it.