Inuvik is small — fifteen minutes' walk end-to-end. The Igloo Church, the greenhouse, the visitor centre, the museum, the supermarket, and most hotels are all within that radius and on foot is the obvious way.
A taxi service runs in town; cars can be rented (book months ahead in summer). For trips out — the Mackenzie Delta, the Tuktoyaktuk Highway, aurora viewing — most visitors use the local tour operators (Tundra North Tours, Arctic Chalet, Up North Tours) rather than self-driving. Renting a vehicle for the Dempster from Whitehorse or Dawson City is more common.