| Silverthorne | E. L. | Kojonup | Buick | KO ● 108 | Kojonup Road Board | 1926-27 |
| Silverthorne | E. L. | Kojonup | Buick | KO ● 108 | Kojonup Road Board | 1927-28 |
| Silverthorne & Adair | - | Kalgoorlie | Napier 12-16 H.P. | K ● 28 | Kalgoorlie Road Board | 1917-18 |
| Silverthorne & Adair | - | Kalgoorlie | Napier 16 H.P. | K ● 28 | Kalgoorlie Road Board | 1919 |
| Silverwood | A. | 35 Money Street, Perth | D.F. Shaw | 3 | Metro Motorcycle | 1922-23 |
| Silvester | A. F. | 175 Barker Road, Subiaco | Chevrolet Wagon | 11812 | Metro Private Car | 1926-27 |
| Silvester | A. R. | Perth Road, Bassendean | Austin | 11952 | Metro Private Car | 1927-28 |
| Silvester | C. E. | 180 Barker Road Subiaco | Buick | 6697 | Metro Private Car | 1924-25 |
| Silvester | C. E. | 180 Barker Road, Subiaco | Buick | 6697 | Metro Private Car | 1925-26 |
| Silvester | E. | 8 Barlee Street | Premier 3½ H.P. Motorcycle | P 840 | Perth Municipality | 1916 |
| Silvester | Marion | 52 Newcastle Street, Perth | Rugby | 2988 | Metro Private Car | 1927-28 |
| Silvester | R. S. | Westonia | Essex | WT ● 81 | Westonia Road Board | 1927-28 |
| Sim | C. | Coombe Street, Collie | Chevrolet | CM 58 | Collie Municipality | 1924-25 |
| Sim | C. | Coombe Street, Collie | Chevrolet | CM 58 | Collie Municipality | 1925-26 |
| Sim | C. | Coombe Street, Collie | Chevrolet | CM 58 | Collie Municipality | 1926-27 |
| Sim | J. R. | Harvey | Ford | H ● 112 | Harvey Road Board | 1925-26 |
| Sim | J. R. | Harvey | Ford | H ● 112 | Harvey Road Board | 1926-27 |
| Sim | J. R. | Harvey | Ford | H ● 112 | Harvey Road Board | 1927-28 |
| Sim | R. D. | Narrogin | Chevrolet 25 H.P. | NA ● 8 | Narrogin Road Board | 1922-23 |
| Sim | R. D. | Narrogin | Ford | NA ● 8 | Narrogin Road Board | 1923-24 |
| Sim | R. D. | Rushy Pool | Chevrolet | NA ● 8 | Narrogin Road Board | 1924-25 |
| Sim | R. D. | Rushy Pool | Chevrolet | NO ● 8 | Narrogin Road Board | 1925-26 |
| Sim | R. D. | Rushy Pool | Chevrolet | NO ● 8 | Narrogin Road Board | 1926-27 |
| Sim | R. D. | Rushy Pool | Chevrolet | NO ● 8 | Narrogin Road Board | 1927-28 |
| Sim | S. P. | Yealering | Dodge | CR ● 84 | Corrigin Road Board | 1924-25 |
| Sim | S. P. | Yearlering | Dodge | CR ● 84 | Corrigin Road Board | 1925-26 |
| Sim | S. P. | Yearlering | Dodge | CR ● 84 | Corrigin Road Board | 1926-27 |
| Sim | S. P. | Yearlering | Austin | CR ● 187 | Corrigin Road Board | 1927-28 |
| Sim | S. P. | Yearling | Chevrolet Truck | CR ● 242 | Corrigin Road Board | 1927-28 |
| Sim | W. | Warriup | Ford Truck | A ● 83 | Albany Road Board | 1927-28 |
| Simeon | J. | General Motors Ltd. Cottesloe Beach | Chevrolet | 15924 | Metro Private Car | 1927-28 |
| Simes | G. | 15 Ord Street, Perth | Essex | 4992 | Metro Private Car | 1924-25 |
| Simes | G. | 15 Ord Street, West Perth | Essex | 4992 | Metro Private Car | 1925-26 |
| Simes | G. | 15 Ord Street, West Perth | Essex | 4992 | Metro Private Car | 1926-27 |
| Simes | G. | 15 Ord Street, West Perth | Essex | 4992 | Metro Private Car | 1927-28 |
| Simkin | H. | Binnu | Chevrolet | NR ● 1 | Northampton Road Board | 1923-24 |
| Simm | S. P. | Corrigin | Austin | CR ● 187 | Corrigin Road Board | 1926-27 |
| Simmonds | G. | Subiaco Road | Car | S 63 | Subiaco Municipality | 1916 |
| Simmonds | J. | Ardath | Morris Cowley | BK ● 286 | Bruce Rock Road Board | 1927-28 |
| Simmonds | W. E. | Cardiff | Chevrolet | CO ● 98 | Collie Road Board | 1927-28 |
| Simmonds | W. R. | Cardiff | Chevrolet | CO ● 98 | Collie Road Board | 1926-27 |
| Simmons | A. T. | 22 Cargill Street, West Perth | Rugdy | 5258 | Metro Private Car | 1926-27 |
| Simmons | A. J. | 5 Longroyd Street. Mount Lawley | Essex | 4301 | Metro Private Car | 1923-24 |
| Simmons | A. T. | 12 Milligan Street | New Hudson 2¾ H.P. Motorcycle | P 144 | Perth Municipality | 1915 |
| Simmons | A. T. | 22 Gargill Street | Douglas 2¾ H.P. Motorcycle | P 1261 | Perth Municipality | 1919 |
| Simmons | A. T. | 22 Cargill Street, Victoria Park | Rugby | 5258 | Metro Private Car | 1925-26 |
| Simmons | A. T. | 22 Cargill Street, Victoria Park | Rugby | 5258 | Metro Private Car | 1927-28 |
| Simmons | Arthur T. | Cargill Street | New Hudson 2¾ H.P. Motorcycle | VP 28 | Victoria Park Municipality | 1916 |
| Simmons | C. | McMillan Street, Victoria Park | Indian 7 H.P. Motorcycle | P 1070 | Perth Municipality | 1917-18 |
| Simmons | C. | 59 Chester Street | Triumph 3½ H.P. Motorcycle | F 14 | Fremantle Municipal Council | 1919 |
