Mexico's new-vehicle sales fell 19.8 percent in March from the year-earlier month to 64,243 cars and trucks, continuing a decline that began last year.
For the first quarter, sales fell 25.9 percent to 195,487.
Mexico's new-vehicle sales slid 6.8 percent in 2008, then tumbled by more than 25 percent in both January and February.
In March, Nissan Motor Co. remained the leader in Mexico, even though its sales fell 21.2 percent to 14,032. For the first three months of 2009, Nissan's sales dropped 31.4 percent to 39,221.
General Motors was second. Its new-vehicle sales skidded 35.0 percent to 10,910 in March and fell 36.7 percent to 35,223 for the quarter.
Volkswagen AG was third but narrowed the gap with GM considerably. Among the top five automakers, VW was the only one to see its sales rise, gaining 6.0 percent to 10,500 in March. But VW's sales still fell 6.5 percent in the quarter to 32,278.
All VW brands but one rose in March. Audi sales jumped 30.5 percent to 441, Seat sales climbed 25.7 percent to 1,052, and VW brand sales gained 3.1 percent to 9,006. Bentley was the only laggard, with sales unchanged at one.
Industrywide truck sales fell more steeply than car sales. Cars fell 17.6 percent in March to 37,374. Truck sales fell 22.7 percent to 26,869.