My husband (driver) and I (front passenger) were in my 2018 Mazda CX-5 Touring and were stopped in traffic on the interstate due to construction. While completely stopped, we were rear-ended by a car traveling at 55-60+ miles per hour (the car did not brake at all before hitting us). Both of our seat backs failed upon impact and went all the way back, with the headrests flying out of both seats. Thankfully no passengers or pets were in the back seat when this happened, but this is a serious safety concern. Attached are photos of the inside of the car in the state it was in after the crash.