Is it permissible to pray behind an imam who is known to associate with non-mahram women and drive them in his car to different places?

Sitting with women and transporting them by car is not considered profligacy if it does not involve *khalwa* (private seclusion) or travel without a *mahram*. However, if *khalwa* with women is established, or excessive talking with them without need, or traveling with them without a *mahram*, then praying behind this person is disliked (*makruh*), and one should seek another imam.