I did something similar years ago when my wife had a friend spend the night. When I left in the morning to go to work, I saw her car behind ours (and another 30' of driveway she could have pulled up in
). Anyway, I get in my truck, back up as usual and hit her car in the rear bumper. No damage to my truck, but $1500 to her POS Honda, Toyota, or what ever it was. It's amazing I saw it, but went into auto pilot when I got and started to back up, just like every other day.