Sterling scored twice for City, in the 19th and 30th minute, while David Silva and Aleksander Kolarov also bagged braces. Marcos Lopes and Jose Pozo rounded off the scoring for the Citizens.
Vietnam's lone goal of the match was scored by midfielder Van Quyet Nguyen, who took advantage of some lazy defending by City in stoppage time and fired the ball past goalkeeper Willy Caballero.
Even though the match finished 8-1 in City's favour, Sterling was still impressed with Vietnam's tenacity and determination throughout the match.
"I thought they put up a good match for us and they fought really hard, but we got a few goals early on and then the goals kept on coming," he told City's official website. "I thought they were a really good side and they had some good players up front.
"As a team, as a collective they were really good, they passed the ball really well and had some good chances and scored the goal."
Sterling has now scored three pre-season goals for City and looks set to be a key figure for the Manchester outift in the upcoming Premier League season.
"My aim is just to take things slowly, do my best playing for Manchester City Football Club and hopefully that will bring me success," he said.
Sterling also thanked all the fans in Vietnam for being so hospitable and added that he cannot wait to return to the Asian nation.
"The most impressive thing [about Vietnam] was the people here – they're really welcoming, they love football and to be welcomed in the way we were was really heart-warming," he said. "I'm really happy to be here and hope I can come back again soon."