[13] Bidders included Metro-Cammell with Singapore Automotive Engineering, Kawasaki with three Japanese manufacturers, MAN with AEG, Siemens and Brown, Boveri & Cie, Francorail with Alsthom-Alantique, SOFRETU and Singapore Shipbuilding and Engineering, ASEA with Sembawang Shipyard, and a Bombardier Transportation-led consortium with Hawker Siddeley Canada and Brown Boveri Canada.

[15][18][19] Metro-Cammell based its design on the Hong Kong MTR M-Train EMU and proposed to use the GEC Traction camshaft resistance control propulsion system had they won the contract.

[13] However, analysts became concerned that a measuring error involving the London Underground 1983 Stock during the evaluation period could jeopardise their bid.

[1][22][23] Kawasaki won the contract; its bid — aided by favourable financing from Mitsui and extremely positive economic conditions in Japan — was 12% lower than those of other bidders, and the 50% lower energy usage of the Mitsubishi GTO-Chopper traction motors in comparison to the GEC Traction camshaft resistance control motors then used on the MTR M-Train EMU was also a major factor in said consortium being awarded the contract.

[27] It was shipped to Singapore and put on public display during the 1984 National Exhibition held in November 1984 at World Trade Centre.

[27] The mock-up featured three choices of seating arrangements and colour schemes; members of the public were invited to give feedback on these options.

The trains were fitted with Stone Platt air-conditioning, Duewag bogies, Narita Mfg gangways and detrainment doors,[29] Scharfenberg couplers and Westinghouse brakes.

[35] On 3 September 2004, Hyundai Rotem, Mitsui, RM Transit Technology and dU LexBuild received an order to refurbish all 396 carriages, costing S$142.7 million in total.

[3] The works included the refurbishment of interior fixtures, the addition of wheelchair spaces, the upgrading of onboard communications equipment, enhancement of the public announcement system, and general improvement of the cars' appearance.

[36] SMRT Corporation said the reasons for refurbishment were wear and damage of important components over the past two decades and water leaks from the air-conditioning system on some trains.

[36] In November 2008, SMRT Corporation and Land Transport Authority (LTA) announced that the last ten refurbished trainsets would have one-third of their seats replaced with metal rails to create extra standing space.

[41][42][43][44] Following major train disruptions on 15 and 17 December 2011, the Committee of Inquiry (COI) found that despite the first refurbishment of the C151 rolling stock, "there does not appear to be any upgrade in terms of engineering components".

The replacement of traction motors into Toshiba PMSM was terminated prematurely by SMRT Corporation in September 2018 due to the New Rail Financing Framework (NRFF).

[49] On 25 July 2018, the contract R151 was awarded to Bombardier Transportation at a sum of $1.2 billion, inclusive of a long-term service support package for up to 30 years.

From 4 October 2024, the C151 trains are limited to run only during the weekday morning and evening peak hours, following the six day long 2024 East-West MRT line disruption.

[58] In November 2006 the doors of three cars (carriage number 1006, 2006 and 3006) were installed with a dynamic, in-train system displaying station information for testing; these are similar to ones used by Hong Kong's MTR.

[59] An initial prototype of STARIS based upon the existing Automatic Transit Info System was developed in-house; this was removed before the end of the year without entering service.

[59] This new SMRT Active Route Map Information System (STARiS) was then progressively introduced to all C151 trainsets, and subsequently to C651 and C751B trains for a cost of S$12 million—S$20,000 per car.

[2][28] The unpainted cars had a shiny appearance upon delivery, but as dirt and grime accumulated it became a recurring problem for the operator and attracted several public complaints.

[61] In response, MRT Corporation built a wash machine at Bishan Depot in an attempt to clean up the cars' exterior proper.

A complete six-car trainset consists of an identical twin set of one driving trailer (DT) and two motor cars (M1 & M2) permanently coupled together.