A car is essential in Susanville. The town itself is small enough to drive end to end in under five minutes, and the main businesses and services are concentrated along Main Street and the adjacent blocks. There is no public transit worth using, and no rideshare service operates reliably here.
For the surrounding area — Eagle Lake, Lassen Volcanic National Park, the Bizz Johnson trailhead — you will need your own vehicle. The eastern trailhead of the Bizz Johnson Trail is within walking distance of downtown, which makes it the one significant attraction accessible without a car. Eagle Lake is about 15 miles north on US-139 and requires a drive.