When 'S' was exhausted at SY, in January 1972, private cars started with E and Land Transport Authority begin to create separate vehicle categories according type of vehicles which previously all vehicles in Singapore must bear prefix S due to previous standardization with Peninsular Malaysia according to geographical location (A is for Perak, B is for Selangor, S is for Singapore/Sabah), motorbikes with A and goods vehicles under 3 tonnes with Y. E was followed by EA, EB with the letters EC in 1973 up to EZ. E was chosen then as letters A-D were already in used by other states in Malaysia. From 1984, the "S" series of number plates was launched again after EZ, but now with two serial suffix letters, starting from SBA, although with several prefixes being skipped as they are reserved, such as SBS and SMB, as they were used for buses that belong to public transport operators. However under the Bus Contracting Model which was later implemented, bus operators under Bus Contracting Model utilise the SG prefix for all public buses.