The billionaire behind six-month-old Vietnamese auto start-up VinFast plans a feat even Toyota and Hyundai couldn’t pull off during their early days: sell a car in the US.Pham Nhat Vuong, the Southeast Asian country’s richest man and now in charge of the new automaker, is so intent on exporting electric vehicles to the lucrative American market in 2021 that he’s ploughing as much as US$2 billion of his own fortune to reach that goal. His cash would account for half the capital investment of…