Kendall Jenner drives her sleek black Ferrari to a Pilates class with her BFF Hailey Bieber... before the models catch an appointment at a hair salon

Kendall Jenner, 26, and her BFF Hailey Bieber, 25, met up for a Pilates class and a salon date in LA on Monday after spending New Year's Eve with Justin Bieber and Devin Booker…