Vietnam Customs said in its latest report that cars imported in the first seven months of the year were worth $1.94 billion, up 319 percent year-on-year. 

Industry insiders said that imports surged because they had hit a trough last year, when the government issued a decree with tougher conditions, requiring importers to provide certain certificates to ensure quality and countries of origin.

But sales could drop this month, the seventh month on the lunar calendar, traditionally called the "ghost month" in which locals avoid buying new things to avoid bad luck.

Nguyen Thi Hien, owner of a showroom in Ho Chi Minh City, said that car consumption usually falls by 30-40 percent in August because of this belief.

Other sales agents said that beginning this month, the number of people visiting showrooms dropped to a handful a day, compared to several dozen the previous month. And those who do come, usually promise to return in September to purchase a car, they added. 

Car brands are offering promotions to boost sales this month. Toyota is offering a discount of VND35-45 million ($1,502-1,931) for the Vios sedans and VND50-60 million ($2,146-2,575) for Innova, a multi-purpose vehicle.

Vietnamese automaker Truong Hai Auto Corporation, which assembles cars for Mazda, is offering a discount of VND100 million ($4,292) for the SUV Mazda CX-5, of which VND50 million ($2,146) would be given in cash and the rest in maintenance package and parts.

Vietnam imported 72,650 cars last year, down nearly 20 percent over 2017, according to Vietnam Customs. But their value exceeded $1.64 billion, up 21 percent.