Is ghusl obligatory if you felt sexually aroused due to a car vibrating, and you found a fluid about which you don't know whether it is maniyy (spermatic fluid) or madhy (prostatic/vaginal fluid), knowing that there was no vibration resulting from the emission of any fluid?

Ghusl (ritual bath) is only obligatory upon the emission of maniy (sperm/seminal fluid) or the penetration of the two circumcised parts. The fluid mentioned might be madhiy (pre-seminal fluid) and not maniy. Maniy is expelled with intense arousal, while madhiy is discharged at the beginning of arousal or when thinking about it. They can be distinguished by their characteristics: Madhiy is a thin, clear, sticky fluid that emerges with arousal without gushing or feeling of orgasm, and is not followed by a decrease in desire. As for a woman's maniy, it is thin and yellowish, and may become white due to her strength. Its signs are pleasure and a subsequent decrease in desire after its emission, or its smell, which is similar to the smell of a man's maniy. If what is discharged from you possesses the characteristics of maniy, then ghusl is obligatory; otherwise, it is not obligatory, and only istinja' (washing the private parts) is required, similar to urination. We warn you against succumbing to obsessive thoughts.