Justin Abdelkader, Patrick Eaves and Tomas Tatar added goals for Detroit, which got 20 saves from Ty Conklin.
The Red Wings close the preseason Sunday against the Penguins.
John-Michael Liles and Joey Crabb lit the lamplight for Toronto, which saw James Reimer stop 22 shots.
The Maple Leafs ended the preseason with a 4-4-0 record. They open the regular season Thursday at home against the Canadiens.