Is it permissible to ride in the car of a person suspected of stealing gasoline from state funds when going to work with him?

There is no religious impediment to riding in a man's car. One must maintain a good opinion of Muslims, based on the Almighty's saying: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin," and on the Prophet's (peace be upon him) saying: "Beware of suspicion, for suspicion is the falsest of speech." It is impermissible to accuse anyone based merely on doubt. There is no suspicion in dealing with a respectable Muslim; and whoever refrains from dealing with him out of piety would be an innovator [in religion].