All have motor driving cabs at both ends each coupled to the trailer power car in the middle (DMA-T-DMB) as opposed to the DM-M-DT configuration.

The train’s body design is similar to its predecessor, albeit with a single air conditioning module in the middle of each carriage.

Selected units previously had a software update installed to enable them to operate slightly higher speeds suitable for the Gold Coast line and would have the markings 'HS' on the right, but this practice was discontinued due to wheel wear issues, and the braking system not being adequately equipped.

[4] Older SMUs have been refurbished to comply with the Australian Disability Discrimination Act 1992[5] with the 220 series having the carpet interiors replaced with hard-wearing Linoleum flooring for low maintenance cleaning, with a blue section for seating compartments separated by red tactile bumps that are situated in doorways.

Dot-matrix displays have been added alongside new automated voice announcement systems on older SMUs (the SMU260s were delivered with them already installed).

[7][8] These units are identical in design to the IMU 160 series trains with the exception of toilets and luggage racks, and the 260s and 160s are also interoperable with each other.