www.chotot.com/
Has new and used, filter search for your area if secondhand be aware that HCMC its 20mill to do plates if the car is outside of HCMC and not on a 51 plate.
Also be aware that some of the adds are take over the payment type sales,, so you will see a newish car for 30mill that's not the actual price so just make sure you know the system before buying.
Best if you know someone who has a car and has done it or is a local and owns one and can tell you more.