SMRT Buses A22s are powered by the MAN D2066LUH-32 diesel engine (10,518cc). Its Exhaust Gas Recirculation (EGR) and PM-Kat filter technology (the latter developed by MAN) does away the need for additives in exhaust treatment, while still able to meet the Euro V emission standards. SMRT Buses opted for a change in transmission model for Batch 4; they are fitted with 4-speed Voith D864.5 automatic transmission which was also the case for Hong Kong A22s.
The bodywork supplied by Gemilang gave the production batch NL323Fs a very different appearance. The exterior design was roughly based on the integral 'Lion's City Hybrid' seen in European countries, but it was neither named as such nor was it a electric-hybrid bus. The unique protruding roof design, which covered the Denso overhead air-conditioning pod, has led to a number of hilarious nicknames given by both the public and bus enthusiasts.
EDS was supplied by Mobitec, which included additional route details on the boarding side of the bus. The interior configuration and design was fully low-floor and similar to the later Batch 2 A22s and Batch 3 with extra standing space at the front of its interior. As with Batch 3, Batch 4 A22s have adjustable air-con outlets installed in response to customer feedback, and "doors are closing" announcements played on these buses whenever the front door closes. Batch Four units were registered SMB1568H, and then from SMB1582R onwards.
At 734 units the MAN A22 is the largest purchase ever in TIBS/SMRT's history for a particular bus model, making it a staple for its contemporary bus fleet and operations.