| Oakley | E. W. | Midland Junction | Overland 20 H.P. | PG 17 | Peppermint Grove Road Board | 1915 |
| Oakley | E. W. | York Road | Overland 18 H.P. | MJ 48 | Midland Junction Municipality | 1916 |
| Oakley | H. H. | Collie | Chevrolet | CM 102 | Collie Municipality | 1927-28 |
| Oakley | H. P. | Three Springs | Chevrolet Truck | CA ● 128 | Carnamah Road Board | 1926-27 |
| Oakley | H. P. | Three Springs | Chevrolet Truck | CA ● 128 | Carnamah Road Board | 1927-28 |
| Oakover Estate | - | Northam | Ford | N ● 160 | Northam Road Board | 1925-26 |
| Oaten | W. | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1924-25 |
| Oaten | W. | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1925-26 |
| Oaten | W. | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1926-27 |
| Oaten | W. | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1927-28 |
| Oaten | W. R. B. | Gabbin | Ford | MM ● 39 | Mount Marshall Road Board | 1926-27 |
| Oaten | W. R. B. | Gabbin | Ford | MM ● 39 | Mount Marshall Road Board | 1927-28 |
| Oaten | William | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1923-24 |
| Oaten | Wm. | Minnivale | Ford | D ● 47 | Dowerin Road Board | 1922-23 |
| Oates | E. E. | Hannan Street | Overland | KMC 116 | Kalgoorlie Municipal Council | 1922-23 |
| Oates | E. E. | Hannan Street | Overland | KMC ● 116 | Kalgoorlie Municipality | 1923-24 |
| Oates | E. E. | Hannan Street | Overland | KMC 116 | Kalgoorlie Municipality | 1924-25 |
| Oates | E. E. | Hannan Street, Kalgoorlie | Overland | KMC 116 | Kalgoorlie Municipal Council | 1926-27 |
| Oates | E. E. | Hannan Street, Kalgoorlie | Overland | KMC 116 | Kalgoorlie Municipal Council | 1927-28 |
| Oates | H. M. | 61 Cecil Street, Victoria Park | Humber 2¾ H.P. Motorcycle | P 245 | Perth Municipality | 1919 |
| Oates | Herbert | 61 Cecil Street, Victoria Park | Humber 2¾ H.P. Motorcycle | P 245 | Perth Municipality | 1917-18 |
| Oates | I. L. | Avonmore Terrace, Cottesloe | Chrysler | 13591 | Metro Private Car | 1926-27 |
| Oates | Mrs E. | Albany | Chevrolet | A 182 | Albany Municipality | 1927-28 |
| Oates | R. K. | Broad Arrow | Ford | K ● 52 | Kalgoorlie Road Board | 1924-25 |
| Oates | W F | Deane Street, Cottesloe | Chrysler | 13591 | Metro Private Car | 1927-28 |
| Oates | W. F. | Deane Street, Cottesloe Beach | Maxwell | 4030 | Metro Private Car | 1923-24 |
| Oates | W. F. | Deane Street, Cottesloe Beach | Maxwell | 4030 | Metro Private Car | 1924-25 |
| Oates | W. F. | Deane Street, Cottesloe Beach | Maxwell | 4030 | Metro Private Car | 1925-26 |
| Oates & Jones | - | Meekatharra | Ford Truck | MK ● 25 | Meekatharra Road Board | 1925-26 |
| Oats | F. W | East Wagin | Ford | W ● 94 | Wagin Road Board | 1926-27 |
| Oats | F. W. | East Wagin | Ford | W ● 94 | Wagin Road Board | 1925-26 |
| Oats | F. W. | Wagin | Overland | W ● 59 | Wagin Road Board | 1927-28 |
| Oats | F. Wm | Wagin | Ford | W ● 94 | Wagin Road Board | 1924-25 |
| Oats | Mrs I. L. | 1187 Hay Street, West | Buick 15 H.P. | P 828 | Perth Municipality | 1917-18 |
| Oats | R. K. | Menzies | Ford 20 H.P. | MN ● 24 | Menzies Road Board | 1922-23 |
| Oats | W. F. | 1187 Hay Street | Buick 20 H.P. | P 828 | Perth Municipality | 1919 |
| Oats | Wm. | 1187 Hay Street, West | Buick 15 H.P. | P 828 | Perth Municipality | 1916 |
| Oats | Wm. F. | 1187 Hay Street | Austin 10 H.P. | P 511 | Perth Municipality | 1915 |
| Oberdorfer | F. | Moora | Reo Truck | M ● 178 | Moora Road Board | 1927-28 |
| Oberin | J. W. | Dwellingup | Rugby | MY ● 22 | Murray Road Board | 1926-27 |
| Oberin | J. W. | Dwellingup | Rugby | MY ● 22 | Murray Road Board | 1927-28 |
| Oborne | L. V. | Tenterden Mount Barker | Ford Truck | PL ● 13 | Plantagenet Road Board | 1924-25 |
| Oborne | Lionel V. | Tenterden | Ford | PL ● 86 | Plantagenet Road Board | 1923-24 |
| Oborne | Lionel V. | Tenterden | Ford | PL ● 86 | Plantagenet Road Board | 1924-25 |
| Oborne | P. T. | Tenterden | Overland | PL ● 99 | Plantagenet Road Board | 1924-25 |
| Oborne | P. Thos. | Tenterden | Dodge | PL ● 23 | Plantagenet Road Board | 1923-24 |
| OCallaghan | J. T | Gilliminning | Chevrolet | WK ● 37 | Wickepin Road Board | 1926-27 |
| Ocean Accident & Guarantee Co Ltd | - | 23 William Street | Hupmobile | 8763 | Metro Private Car | 1925-26 |
| Ocean Accident & Guarantee Co Ltd | - | 23 William Street, Perth | Hupmobile | 8763 | Metro Private Car | 1926-27 |
| Ocean Accident & Guarantee Corp. Ltd | - | Saint George's Terrace | Singer 3½ H.P. Motorcycle | P 91 | Perth Municipality | 1915 |
