The yellow cars that are driven underground were World War II-era German military vehicles made by Volkswagen, called a "Kübelwagen." The car wasn't sold to the public until 1971, where it was renamed the "Thing" in the USA, and "Trekker" in the UK.
Shown on Turner Classic Movies (TCM) in January 2021 and again in October 2022.
Many of the features in the film are reminiscent of the James Bond movies from the same era: the underground complex, the Asian villain and female protagonist, fast cutting, and the contemporary sound of the musical score. The closest comparison would be "Doctor No" (1962).