Sales of new cars and light trucks in Mexico fell to 80,120 in March, down 16.9 percent from March 2007.
Through the first quarter, retail sales totaled 263,942, down 5.8 percent from the year-earlier period, according to the Mexican Automotive Manufacturers Association.
March's double-digit drop followed a 1.1 percent gain in February. That had been the first sales increase since a 1.1 percent rise in January 2007.
Of the five top-selling carmakers in Mexico, Nissan Motor Co. backed into first place as its sales slipped just 3.0 percent, to 17,802 in March. That put it ahead of General Motors, whose sales fell 19.5 percent to 16,791. Nissan's car sales fell, but its truck sales rose.
Volkswagen AG came in third with sales of 9,907 vehicles, down 25.8 percent. Chrysler LLC's March sales dropped 11.0 percent to 9,886.
Ford Motor Co. suffered the biggest contraction among the sales leaders. Its March sales plummeted 35.5 percent to 9,559, dropping Ford from third place in March 2007 to fifth place in March 2008.
Mazda Motor Corp. stood out with the only sales increase in March among automakers with sales of at least 1,000 units. Mazda sales jumped 11.5 percent to 1,512.
Toyota Motor Corp.'s March sales fell 11.2 percent to 5,156. Honda Motor Co.'s sales fell 12.4 percent to 3,699.
Mitsubishi Motor Corp.'s sales fell 5.9 percent to 1,412. Renault SA's sales slumped 21.7 percent to 1,286.