During a crash, a seat belt's pretensioner pulls in on the belt to help keep you safe. But the pretensioner in the 2017 Audi A5 Cabriolet and S5 Cabriolet is anything but safe according to CarComplaints.com:
"the micro-gas generator within the pretensioner could detach during a crash and become a dangerous projectile."
Seat belt missiles? That's a new one. The pretensioner recall is expected to begin in May 2017.