Was the action of the questioner in chasing a car, under the assumption that there was a wrongful act, a mistake that warrants a troubled conscience?

It is not permissible to harbor ill-will towards people without evidence, for Allah Almighty says: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin." And the Prophet, peace and blessings be upon him, said: "Beware of suspicion, for suspicion is the most mendacious of speech." A pang of conscience may be a good sign and a sign of remorse. It is advised to sincerely repent to Allah. If possible, meeting the man and seeking his forgiveness without disclosing what happened is preferable, provided no harm results from it. Otherwise, increase your seeking of forgiveness and supplication for him.