Fatwa : Praying Nawafil in a car

Q : May a driver and likewise a passenger perform nafil prayers in a car, gesturing for bowing and prostration?

A : Yes. By analogy with one riding a mount: he says the takbīr, recites, and gestures for bowing and prostration; facing the qiblah is not required here.

- Syed Muhammad Abdullah Awad

Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1