The initiative was launched by Transport Minister Simon Bridges and Associate Minister Crag Foss today.
Mr Bridges said if the trial was successful, the initiative may continue along the route and be implemented in other parts of New Zealand.
"The New Zealand-designed transmitters are in remote locations where there is no mobile coverage. This feature, and the use of Bluetooth technology, makes the trial the first of its kind in New Zealand for in-vehicle messaging."
The trial is being run by the NZ Transport Agency (NZTA), in partnership with HMI Technologies and GO Rentals.
Mr Foss said while the trial did not not specifically target visiting drivers, NZTA would assess whether the service could be added to its suite of safety measures.
"This technology has the potential to improve safety outcomes in remote locations, which are draw-cards for many overseas visitors.
"If the trial is successful, a second step could be to create a mobile phone application that allows communication with the vehicle's internal audio system, making the initiative more accessible to all road users."