The Adelaide Metro 4000 class, also referred to as A-City trains,^[3] are electric multiple unit trains built by Bombardier Transportation (later Alstom)^{[lower-alpha 1][1]} in Dandenong, Victoria for the electrified Adelaide rail network. They are the only class of operational electric trains in South Australia,^[4] running services on the Gawler, Seaford and Flinders lines.

The design shares similarities to the V/Line VLocity and Transperth B-series trains, also built by Bombardier.^[3]

In March 2011, Bombardier Transportation was awarded a contract to build 22 three-carriage trains for the Adelaide rail network, that was in the process of being electrified.^[5][6][7] The first of the Adelaide trains was delivered in July 2013, and entered service on 23 February 2014 on the Seaford and Tonsley (now Flinders) lines.^{[8][9][10][11][12]} The last was completed in October 2015.^[13][14]

When they were ordered, it was proposed that the Gawler line would be electrified, which would allow the trains to access Adelaide Metro's Dry Creek depot. However, before they were delivered, that project was temporarily cancelled. Whilst light maintenance was performed at their primary stabling point at Seaford Meadows, heavy maintenance needed to occur at Dry Creek. When required, each train was hauled there from Adelaide station by a pair of 3000 class railcars. This movement was ceased once the Gawler line was electrified in 2022.^[15]

In June 2019, a further 12 train sets were ordered for the Gawler line electrification, the first of which was delivered in mid-late 2021 and entered service on 4 March 2022.^[16]