Stoltenberg said he wanted to hear what voters really think and that cab is one of the few places where people can share their true thoughts.
He was carrying glasses and uniform taxi driver in June and reveal his identity only after the passengers knew. His conversations with travelers capture hidden camera.
Also, there is no passenger having to pay for service, and the recording will be used for his campaign before the September elections in Norway.
Stoltenberg is very popular in Norway, but, according to recent polls, he lags behind the opposition.
When asked whether it believes that the taxi driver if he loses the election, Stoltenberg said that "thinks Norwegian passengers will be better, to serve as prime minister than as a driver."