Confusion and uncertainty reigned in the deeply integrated North American auto industry on Thursday, the day the Trump administration hit imports with a hodgepodge of tariffs. 

"Everyone is confused," said Peter Frise, an automotive expert at the University of Windsor. 

Faced with few new details from the White House, industry insiders on both sides of the border were struggling to understand how, exactly, the U.S. government will apply tariffs to the truckloads of vehicles and parts crossing the…