Not even the new Mustang could stop Ford's slide.
New vehicle sales fell nearly three percent in May. Ford says the retro coupe sold at a blistering pace, up 47 percent from last May.
But it wasn't enough to offset a 6.4 percent loss in truck sales. Ford's total sales are off four percent for the first five months of the year.
Nissan, meanwhile, had a record May with a 15.5 percent increase in sales. Officials say the Armada SUV led the way.