1. I suffered a seatback failure in my 2018 Acura RDX when I was rear-ended at a high speed. The car is currently with my insurance company but I'm sure it's available for inspection. 2. The seatback failure made a big enough gap between my seat and seatbelt for me to slip completely under my seatbelt. I landed on the backseat floor after I smacked my head on the side rear airbag. I have multiple injuries from the seatback failure and my children would have been hurt from this failure had they been in the car with me. 3. N/A 4. The vehicle was totaled. The insurance adjuster said all seats "had shifted". I asked if that was another word for "broken". He said "yes". 5. No warnings appeared. The car was in perfect working order.