A good question.
A local answer.

If Hobart city days do not require the car, compare a later pickup with the cost of transfers for those days.

If the car is only needed later, price collecting it after the walkable Hobart days.

Compare the total price for airport and city pickup, including the cost of getting to an off-airport desk.

If stock is uncertain, look for a licensed local hire or transfer option rather than travelling without a legal restraint.

Compare confirmed rental terms and cancellation policies early; a speculative hourly car is risky during a busy holiday.

Read the posted street-parking rules carefully, especially on weekends or during events.

Market morning can make nearby streets busy, so arrive early or choose a slightly farther space with a straightforward walk. Check road closures and event notices for that Saturday.

Price only the days you need a car and use the city stay for walking or booked transport. Also compare airport and city depots after adding transfer and parking costs.

Price airport transfer, city pickup and one-way return fees together with parking savings. The cheapest daily rate may not be the cheapest plan.

Compare the complete weekend cost with hotel parking and on-street limits, including the walk back after dark. Do not rely on an old forum price.