Judging from their clothes (the suspenders, the night club, Mist's singing costume) in that era it's look like they're in the 1950s. China's automotive industry also started in the 1950s. So, it might be possible.
Idk much about Chinese culture but isn't that more of a sign of it being somewhere around 20-40's? It's also during a war.
Around that time might still be possible for cars to be around, they would just be more rare since the industry wouldn't have started yet and mainly the wealthy would probably have them. The first vehicle was invented in 1886.
It's cute n all but Bitch hold on they have CARS in that era, I am confusion