The NZR RM class Wairarapa railcar was a class of railcars on New Zealand's national rail network. They entered service in 1936 (three weeks after the Midland railcars) and were classified RM like all other classes of railcars in New Zealand; they came to be known as the "Wairarapa" class as they were designed to operate over the famous Rimutaka Incline to the Wairarapa region on the Wairarapa Line. They also acquired the nickname of "tin hares" in New Zealand railfan jargon. The first two to be introduced re-used the numbers RM 4 and RM 5 that had previously been used by the withdrawn experimental Model T Ford railcars. The class consisted of six passenger railcars and one passenger-freight railcar. It is often described incorrectly as a class of six railcars.