While slowly backing out of a parking space, the vehicle suddenly accelerated on it's own - I do not recall pressing on the accelerator but the engine surged and the vehicle rapidly reversed and struck 4 other parked cars. It felt as if the accelerator became stuck and would not respond to braking. No warning light or dashboard alerts appeared. Subaru eyesight and adaptive cruise control were not engaged at the time. There was no known obstruction under the petals. This felt like a serious malfunction and could have caused serious injury. I am reporting this in case it is part of a wider issue affecting this model and because i see that there are multiple complaints to you about sudden unintended acceleration, especially during low speed maneuvers like backing out a parking space.