Katowice is a separate airport from Kraków. Compare the full onward journey and any one-way fee between branches.
The airport lists the rental-company offices in Terminal C. Confirm your supplier’s hours, flight details and vehicle location rather than going to a departure terminal desk.
A car is useful for rural accommodation, lake districts and a route with stops beyond the main rail corridors. Warsaw, Kraków, Gdańsk and Wrocław city stays can be separated from the driving days to avoid paying for unused parking.
Compare airport collection with a later collection if you start with a city stay. Include the transport to a different rental branch and any extra parking nights when comparing the total cost.