.. you cannot play "Freak Drive", if that "Freak Drive" is drawn as replacement for a card that has the "Do not replace until end of action" clause on it (e.g. "Arson" or "Gramle"). This is because the action has ended and there is no longer an opportunity to play the action modifier.
On the other hand, you can play "Freak Drive" if the card is drawn as replacement for a card that has the "Do not replace until after combat" (e.g. "Dodge") clause on it, since the action hasn't been concluded yet.
References: Usenet Newsgroup/Monocle of Clarity.