Downtown Montpelier is genuinely walkable — the State House, Main Street, Elm Street, and the Winooski riverbanks are all within a fifteen-minute stroll of each other. Most visitors park once and leave the car for a day.
For trips out of town, you need a vehicle. Green Mountain Transit runs city buses around Montpelier and Barre on weekdays; useful for the train station and a few outlying stops, but not really suitable as a primary travel mode. Taxis are available but the supply is thin; ride-shares operate but cover thins out on evenings and weekends.