HANOI, Oct 10 (Reuters) - Vietnam's total vehicle sales fell by 20 percent to 21,216 units in September from a year earlier, the Vietnam Automobile Manufacturers' Association (VAMA) said on Tuesday. September sales by VAMA member-manufacturers also dropped 20 percent from the same month last year to 19,257 units, including commercial vehicles, passenger cars and special-purpose vehicles. Vietnam's Truong Hai Auto Corp, which assembles sedans, trucks and buses, led the sales in September, followed by Toyota Motor Corp. Month-on-month, September sales of passenger cars were down 7 percent, while commercial vehicle sales were the same and special-purpose vehicles rose 4 percent, VAMA said in a report. The following table shows data provided by VAMA: 2017 2016 Month *Sept Aug July June May April March Feb Jan Dec Nov Oct Units 21,216 22,099 20,662 24,365 23,232 21,942 26,872 17,621 20,232 33,295 28,442 28,283 Y/y pct -20 -6 -27 -0.2 -11 -15 8 50 -13 13 -4 26 NOTE: Data from January 2017 onwards shows industry-wide sales instead of VAMA member-only sales as in previous months. (Reporting by Mai Nguyen; Editing by Sunil Nair)