The Overlander replaced a previous service operated by RM class Silver Fern railcars on Monday 2 December 1991.

On 18 August 2006, the Green Party announced a Save the Overlander campaign, which received a positive response, primarily from the small towns along the train's route.

Externally, the three former Bay Express cars and seven existing Overlander cars retained the Cato blue paint scheme of the Tranz Rail era, but with the new "Overlander" promotional logo introduced by Toll Rail on the sides in large white letters.

[4] In mid-2009, it was announced that patronage had steadily increased and that the service was thriving with 25.5% more passengers over the previous year, and that additional carriages had been added to the train in some cases to satisfy demand.

In December 1991 another modular van was refitted with a generator, and a Wairarapa Connection car with 32 seats to a newer design arranged alcove-style and a servery to facilitate the introduction of a third trainset for maintenance requirements, the third set thus becoming a spare.

The former Vice-Regal (Governor-General) car turned Southerner full buffet car was refitted in 1993 and returned to the NIMT with 24 seats to a newer design arranged alcove style and a short buffet counter to replace the full-length counter and 20 bar stools.

As the Overlander and Northerner shared rolling stock, substantially better carriage utilisation was achieved, compared to having two train sets sitting unused for over 12 hours a day.