Is it safe to recline my seatback while the vehicle is moving?

No, you should not have a seatback reclined while the vehicle is in motion. A reclined seatback means the shoulder belt cannot do its job, and in a crash you could slide under the lap belt, causing serious internal injuries. For proper protection, keep the seatback upright, sit well back in the seat, and wear your safety belt properly. (Page 13)