You can't count on the PDC to be your 3rd eye on the back of your head. I was mowing my lawn one day and decided, heck, let's just take a break and park the mower right outside the garage, right behind my X5. Then went in, took a shower, and wife asked to get something for her from the store. "Sure, honey, brb", got in the X5 and backed up. BANG! Backed right into the lawn mower handle and scratched the lenses of the brake lights. No warning whatsoever from the PDC.