Mercedes-Benz O305

After evaluating the two Mercedes-Benz O305 double-decker buses acquired in 1982, Singapore Bus Services purchased 200 Mercedes-Benz O305 double-decker buses which were very similar to KMB's O305s. They featured an 11,412 cc OM 407h engine with its modular W3D 080 R gearbox. With a licensed capacity of 109 passengers, they were the largest non-air conditioned double-decker buses in Singapore. They entered service in 1985 with the last retired by late 2001.

Most of the buses were de-registered between 1998 and 2001. SBS2477X, SBS2478H - SBS2592X were replaced by Volvo Olympian 3 Axle (Batch 3), SBS7027D - SBS7112R were replaced by last 50 units of Volvo B10M Mark IV (DM3500) and Dennis Tridents. The short-haul feeder service O305 were replace by Volvo B10M Mark IIs.