Question: If someone falls asleep sitting on a car seat, with his bottom staying firmly on the seat whilst leaning back, will his wudu break?
Answer: Wa alaikum assalam wa rahmatullah,
I pray this message finds you in the best of health and faith, insha’Allah.
No, sleeping with your rear firmly seated does not invalidate your wudu. [Shurunbulali, Maraqi al-Falah]
And Allah alone gives success.