Ho Chi Minh City's government has asked the Ministry of Transport to overturn a ban on low-cost carpooling services that was issued in June.
The ministry previously said it would not allow either Grab or Uber to offer their ridesharing services GrabShare and UberPOOL in Vietnam because sharing a car with a stranger puts passengers at risk
The decision came a month after the two ride-hailing firms rolled out their services in the city.
If Uber and Grab disobey the rule, they will be fined VND4-6 million ($175-260) per ride, the ministry said.
But the ministry's words seem to have been an empty threat because GrabTaxi is still offering the service, and has also asked for the ban to be lifted, local media reported.
The ministry asked for the city's opinion in July. In response the city said it said it is difficult to tell if a Grab or Uber driver is offering a ridesharing service, so it's nearly impossible to stop them.
It also said carpooling services are convenient for passengers because they cost less, and more importantly, reduce traffic congestion in the city.
The city has asked the ministry to allow a carpooling service to be piloted for one year so that it can build regulations to manage it.
As suggested by the city, only cars with less than nine seats will be allowed to operate the service, and each car can only accept two contracts at once. They must also have specific logos to distinguish them from those that do not offer the service.
HCMC is looking at ways to limit the number of private vehicles entering the city center to ease congestion.
Official data show that the city's transport department had licensed 23,820 cars with under nine seats as of June 30 this year.
By mid May, the city had more than 8 million private vehicles, an increase of 5.8 percent against the same period last year, including 646,400 private automobiles and 7.4 million motorbikes.
The current number of autos in the city has nearly tripled the limit set for 2020 and is double the ceiling set for 2025.
At a meeting with local residents in August, Mayor Nguyen Thanh Phong said the city would revisit a plan to change school and office hours in an attempt to stagger the amount of traffic hitting the city's streets during rush hours.
Research conducted by Associate Professor Pham Xuan Mai from the Ho Chi Minh City University of Technology released in March last year found that traffic congestion costs the southern metropolis more than VND18.3 trillion ($820 million) every year.