By the 1970's there was a pressing desire to replace the ageing passenger equipment on the Victorian system. The average age of the cars was about 60 years old. From the late 1970's a new set of car designs were drawn up.
The cars were built using car shell designs from the 1950's but featured different internal layouts, air conditioning, power doors. Power supply was provided by a motor generator set slung beneath the car. Up to this date power supply was either belt drive from the bogie axle or head-end power on larger express trains. Head-end power allowed more cars per train as belt drive resistance was considerable.
The First Class cars were fitted with a guards section which provided for train safeworking equipment and luggage stowage. The cars were coded ACN.
As the same number group was used for three types of cars, the ACN numbers were non consecutive. As issued the cars were in sets of three. ACN 3, 6, 9 were issued in 1981. Cars 12, 15, 18, 21, 24, 27, 30, 33, 36 were issued in 1982. Cars 39, 42, 45, 48, 51, 54 entered service in 1983.
The cars are generally called 'N' cars and were known internally as 'Norman' cars, after a Railway Commissioner.
When issued the cars were painted orange with silver trim and VicRail 'Teacup' logo. With the introduction of the V/line trading name, the cars were repainted with V/line logo.
From about 1995, the corporate colour scheme was changed to maroon and blue.