It's been a while since this actually happened, but here are some photos from me going into the back of a car at ~50km/h.
I was head down hurting at the start of morning peak hour and didn't see the parked car in a clearway/towaway zone until the last second. I had enough time to throw myself to the right and the bike went square into the back of the car. I took off the right hand side external mirror as I went past, and tucked and rolled as I landed about 2 metres in front of the car.. Didn't even crack my helmet on landing. Effectively got up and walked away but was taken to hospital emergency for a few hours to go over me. Just a couple of small scars which are not all that visible now 2 or so years ago.
I never 'suffer' while training or racing with my head down now. Something I try to teach everyone else to do.
Good advice. Check out the rest of the photos.