| Irwan | Dr. | Boulder | Ford 16-20 H.P. | BMC 3 | Boulder Municipality | 1915 |
| Irwin | Dr H. O. | 42 Moran Street, Boulder | Dodge | B 38 | Boulder Municipality | 1925-26 |
| Irwin | Dr H. C. | Moran Street, Boulder | Dodge | B 38 | Boulder Municipality | 1927-28 |
| Irwin | Dr H. O. | Boulder | Ford 16-20 H.P. | BMC 3 | Boulder Municipality | 1917-18 |
| Irwin | Dr H. O. | 42 Moran Street, Boulder | Dodge | B 38 | Boulder Municipality | 1924-25 |
| Irwin | Dr H. O. | 42 Moran Street, Boulder | Dodge | B38 | Boulder Municipality | 1925-26 |
| Irwin | Dr H. O. | 42 Moran Street, Boulder | Dodge | B 38 | Boulder Municipality | 1926-27 |
| Irwin | Dr. | Boulder | Ford 16-20 H.P. | BMC 3 | Boulder Municipality | 1916 |
| Irwin | Dr. H. O. | 42 Moran Street, Boulder | Dodge | B 38 | Boulder Municipality | 1923-24 |
| Irwin | H. O. | 42a Brookman Street, Boulder | Dodge | B 3 | Boulder Municipality | 1922-23 |
| Irwin | R. | Gnowangerup | Ford | GN ● 129 | Gnowangerup Road Board | 1926-27 |
| Irwin | R. | Gnowangerup | Ford | GN ● 160 | Gnowangerup Road Board | 1927-28 |
| Irwin | S. | Comer Street, Como | Oldsmobile | 3569 | Metro Hire or Trade | 1926-27 |
| Irwin | W. A. | 13 Colin Grove West Perth | Ford Wagon | 14989 | Metro Private Car | 1927-28 |
| Isaac | B. Rose | Jarring | Dodge | LG ● 1 | Lake Grace Road Board | 1923-24 |
| Isaac | W. | Nedlands Park | Ford | CL 15 | Claremont Road Board | 1916 |
| Isaac | W. | Viewway, Nedlands | Car | CL ● 15 | Claremont Road Board | 1917-18 |
| Isaac | W. | Broome Street | Studebaker 20 H.P. | Ce 1 | Municipality of Cottesloe | 1917-18 |
| Isaac | W. | Vieway, Nedlands | - | CL ● 15 | Claremont Road Board | 1919 |
| Isaac | W. | Broome Street | Studebaker 20 H.P. | Ce 1 | Municipality of Cottesloe | 1919 |
| Isaacman | J. | 250 Lake Street | B.S.A. 3½ H.P. Motorcycle | P 138 | Perth Municipality | 1915 |
| Isaacs | C. F. | 23a Cargill Street, Victoria Park | Ford Wagon | 3567 | Metro Private Car | 1924-25 |
| Isbesser | F. W. | Bendwood Parade, Nedlands | Citroen | 6457 | Metro Private Car | 1924-25 |
| Isbester | F. W. | Bendwood Parade, Nedlands | Citroen | 6457 | Metro Private Car | 1925-26 |
| Isbester | F. W. | Birdwood Parade, Nedlands | Chrysler | 2319 | Metro Private Car | 1927-28 |
| Isbister | E. | Williams | Austin | WL ● 100 | Williams Road Board | 1927-28 |
| Isbister | F. | Nedlands | Morris-Oxford | 2318 | Metro Private Car | 1926-27 |
| Isbister | F. E. | York | Citreon | Y ● 63 | York Road Board | 1923-24 |
| Isbister | F. W. | - | Morris Oxford | Y ● 21 | York Road Board | 1917-18 |
| Isbister | F. W. | - | Morris-Oxford 10 H.P. | Y ● 2 | York Road Board | 1919 |
| Isbister | J. | Williams | Chrysler | WL ● 99 | Williams Road Board | 1927-28 |
| Isbister Bros | - | Williams | Ford 15 H.P. | WL ● 14 | Williams Road Board | 1917-18 |
| Isbister Bros | - | Williams | Ford 10 H.P. | WL ● 14 | Williams Road Board | 1922-23 |
| Isbister Bros | - | Williams | Ford | WL ● 14 | Williams Road Board | 1925-26 |
| Isbister Bros. | - | Williams | Ford 15 H.P. | WL 14 | Williams Road Board | 1916 |
| Isbister Bros. | - | Williams | Ford 10 H.P. | WL ● 14 | Williams Road Board | 1923-24 |
| Isbister Brothers | - | Williams | Ford | WL ● 14 | Williams Road Board | 1924-25 |
| Islam | Mrs J | 10 Almondbury Road, Mount Lawley | Essex | 4544 | Metro Private Car | 1924-25 |
| Islam | Mrs J. | 10 Almondsbury Road, Mount Lawley | Essex | 4544 | Metro Private Car | 1925-26 |
| Isle | F. | - | Vulcan Truck | M ● 78 | Moora Road Board | 1925-26 |
| Isle | F. H. | - | Vulcan Truck | M ● 78 | Moora Road Board | 1926-27 |
| Isle | F. H. | - | Vulcan Truck | M ● 78 | Moora Road Board | 1927-28 |
| Isle | J. | Moora | Chevrolet | M ● 201 | Moora Road Board | 1927-28 |
| Ison | S. | - | Overland | N ● 79 | Northam Road Board | 1927-28 |
| Issacman | J. | Perth | B.S.A. 4¼ H.P. Motorcycle | GN 33 | Geraldton Municipality | 1916 |
| Issell | F. M. | Gregory Street, Geraldton | Hupmobile 26 H.P. | GN 6 | Geraldton Municipality | 1922-23 |
| Issell | F. M. | Gregory Street, Geraldton | Hupmobile 26 H.P. | GN ● 6 | Geraldton Municipality | 1923-24 |
| Ittershagen | C. | Railway Road, West Perth | Dealers | 20277 | Metro Dealers Car | 1927-28 |
| Ittershagen | H. C. | Railway Road, West Subiaco | Dealers | 20227 | Metro Dealers Car | 1927-28 |
| Ivanhoe G. Corporation | - | Kalgoorlie | Sunbeam 12-16 H.P. | K ● 15 | Kalgoorlie Road Board | 1917-18 |
