Backing out of the garage then stopping for a minute and putting it in park then in drive afterwards I forgot there was a car behind me in my driveway. After looking in my side mirrors i saw nothing. I hit the vehicle behind me. With the radio on and playing music at no time did the radio lower in sound and the avoidance system sound off. If the avoidance system sounded off the music was louder. I hit the vehicle behind me. I guess i should have turned my head to check behind me but if the sounds were going off it might have helped me to avoid this. I really can't remember either if the camera was on. Usually if the sounds start chirping i look towards the screen. There was no damage to my vehicle only the vehicle i hit. It was my rear spare tire that caused the damage on the other vehicle. I will need to take the family vehicle to get an estimate.