India, Sept. 9 -- India's passenger vehicle industry suffered its worst-ever monthly sales performance in August as a protracted demand slowdown showed no signs of abating.

Companies did not step up production of vehicles fearing sales will continue to stay weak during the crucial festive season, which begins this month and continues till late October. Car sales in India are measured as factory dispatches and not retail sales.

Domestic sales of passenger vehicles plunged 31.6% in August to 196,524 units from a year earlier, according to data released by the Society of Indian Automobile Manufacturers (Siam) on Monday. It was the 10th straight decline in domestic passenger vehicle sales and the worst since Siam began compiling monthly sal...