First generation
Known as the "red rattlers" by Sydney residents, the first generation of suburban electric rolling stock was introduced from 1926, the same year the first electrified line opened in the Sydney suburban network. The original carriages had wooden bodies, but later versions boasted steel-bodied design. These carriages provided sterling service for over 60 years and were all withdrawn by 1993.

Second generation
The second generation of suburban electric rolling stock began service in 1964 and includes the 1964 vintage Tulloch trailers which were of aluminium construction. Then, in 1972, the first of the stainless steel types appeared. They were a radical departure from the first generation in that they introduced double deck carriages to the Sydney suburban network.

Third generation
Tangara trains are the third generation in CityRail's electric fleet. They were introduced from 1988 and are still in service. The Tangara introduced the latest technology and modern streamlined styling which clearly differentiated them from previous generations. The Tangara was also the first named train on the Sydney suburban network, deriving its name from the Aboriginal word for “to go”.

Fourth generation
The fourth generation Millennium trains represent yet another leap in terms of design standards, comfort and technology. Although similar to Tangaras, the Millennium trains are a result of changing customer expectations in terms of internal design.

The new Oscars are another example of fourth generation of suburban electric rolling stock.