| Oma | A. W. | 177 Rokeby Road, Subiaco | Ford | 7452 | Metro Private Car | 1926-27 |
| Oma | Arthur W. | 84 Broome Street, Perth | Harley Davidson | 1126 | Metro Motorcycle | 1922-23 |
| Oma | H. W. | Kalamunda | Lacre Wagon | DR ● 35 | Darling Range Road Board | 1924-25 |
| Oma | L. E. | 36 Byars Road, West Midland | Chevrolet | 4602 | Metro Private Car | 1925-26 |
| Oma | Mrs L. E | 24 Wittenoom Street, East Perth | Chevrolet | 4602 | Metro Private Car | 1927-28 |
| Oma | Mrs L. E. | 24 Wittenoom Street, East Perth | Chevrolet | 4602 | Metro Private Car | 1926-27 |
| Oma | Mrs R. A. | 36 Byars Road, West Midland | Chevrolet | 4602 | Metro Private Car | 1924-25 |
| Oma | Mrs V. A. | 177 Railway Road, Subiaco | Fiat | 9461 | Metro Private Car | 1927-28 |
| Oma | V. C. | 308 Onslow Road, Subiaco | Ford Wagon | 12937 | Metro Private Car | 1927-28 |
| Omadie | P. | Toodyay | Chevrolet Truck | T ● 78 | Toodyay Road Board | 1927-28 |
| Omadie | Peter | Toodyay | Reo Truck | T ● 65 | Toodyay Road Board | 1927-28 |
| Omar | H. W. | 19 Woodbridge Terrace, Midland | Napier | 3152 | Metro Private Car | 1922-23 |
| Omar | H. W. | 19 Woodbridge Terrace, Maylands | Napier | 3152 | Metropolitan Hire and Trade Cars | 1923-24 |
| Omer | H. W. | Midland Junction | Lacre truck | DR ● 33 | Darling Range Road Board | 1923-24 |
| Omer | H. W. | Midland Junction | Centenell | DR ● 35 | Darling Range Road Board | 1923-24 |
| Omeroed | A. | Fitzgerald Street | B.S.A. 3½ H.P. Motorcycle | N 13 | Northam Municipality | 1916 |
| Omodei | J. J. | Hay Street | Ford Truck | KMC 171 | Kalgoorlie Municipality | 1924-25 |
| Omodel | G. | Osborne Park Hotel, Osborne Park | Dodge | 1685 | Metro Private Car | 1927-28 |
| Omodel | J. | 227 Hay Street | Ford Truck | KMC 171 | Kalgoorlie Municipal Council | 1925-26 |
| Omodie | P. | Toodyay | Chevrolet Truck | T ● 78 | Toodyay Road Board | 1926-27 |
| ONeill | D. I. | Tambellup | Ford | TA ● 38 | Tambellup Road Board | 1927-28 |
| Onions | B. L. | Busselton | Hupmobile | BN 45 | Municipality of Busselton | 1925-26 |
| Onions | B. L. | Busselton | Hupmobile | BN 45 | Municipality of Busselton | 1926-27 |
| Onions | B. L. | Busselton | Hupmobile | BN 45 | Municipality of Busselton | 1927-28 |
| Onions | E. E. | East Street | Douglas 2¾ H.P. Motorcycle | F 94 | Fremantle Municipal Council | 1919 |
| Onions | E. E. | Cnr. East & Forrest streets, East Fremantle | Chev. | 869 | Metro Private Car | 1924-25 |
| Onions | E. E. | East & Forrest streets, East Fremantle | Chevrolet | 869 | Metro Private Car | 1925-26 |
| Onions | E. E. | Forrest Street, Fremantle | Essex | 12535 | Metro Private Car | 1927-28 |
| Onions | Edgar E. | Cnr. Forrest & East Streets | Douglas 2¾ Motorcycle | F 94 | Fremantle Municipal Council | 1917-18 |
| Opie | H. | Marine Terrace, Geraldton | Overland | GN 48 | Geraldton Municipality | 1924-25 |
| Opie | H. | 32 Mount Street, Perth | Chrysler | 14860 | Metro Private Car | 1927-28 |
| Opie | H. H. | Marine Terrace, Geraldton | - | GN 115 | Geraldton Municipality | 1925-26 |
| Opie | H. H. | 19 Economic Chambers, Perth | Essex | 13103 | Metro Private Car | 1926-27 |
| Opie | W. H. | 593 Beaufort Street, Perth | Chevrolet Wagon | 3700 | Metro Hire or Trade | 1925-26 |
| Opitz | C. | Keysbrook | Overland | SJ ● 39 | Serpentine-Jarrahdale Road Board | 1925-26 |
| Opitz | C. | Keysbrook | Overland | SJ ● 39 | Serpentine-Jarrahdale Road Board | 1926-27 |
| Opitz | C. | Keysbrook | Overland | SJ ● 39 | Serpentine-Jarrahdale Road Board | 1927-28 |
| Opitz | Louis Ernest | Keysbrook | B.S.A. 4 H.P. Motorcycle | SJ ● 2 | Serpentine-Jarrahdale Road Board | 1922-23 |
| Ople | W. H. | 598 Beaufort Street, Perth | Chevrolet | 3700 | Metro Hire or Trade | 1926-27 |
| Opperman | A. | Greenbushes | Ford | GR ● 35 | Greenbushes Road Board | 1926-27 |
| Opperman | A. | Greenbushes | Ford | GR ● 35 | Greenbushes Road Board | 1927-28 |
| Opperman | H. A. | Mingenew | Chevrolet Truck | MI ● 25 | Mingenew Road Board | 1927-28 |
| Oppermann | H. A. | Mingenew | Overland Truck | MI ● 25 | Mingenew Road Board | 1926-27 |
| Oqilvle | Mrs E. M. | 123 Saint George's Terrace, Perth | Whippet | 1463 | Metro Private Car | 1927-28 |
| Oralia Manufacturing Co | - | 167 William Street, Perth | Chevrolet | 11311 | Metro Private Car | 1926-27 |
| Oralia Manufacturing Co | - | 167 William Street | Chevrolet | 11311 | Metro Private Car | 1927-28 |
| Orchard | D. J | Wickepin | Graham Truck | WK ● 43 | Wickepin Road Board | 1926-27 |
| Orchard | D. J | East Wickepin | Dodge | WK ● 69 | Wickepin Road Board | 1926-27 |
| Orchard | D. J. | East Wickepin | Dodge | WK ● 69 | Wickepin Road Board | 1925-26 |
| Orchard | D. J. | Wickepin | Dodge | WK ● 123 | Wickepin Road Board | 1925-26 |
