Want your own car, but just for a short while? Here's an option. Download the Traficar app, find an empty vehicle (their clearly-marked fleet includes 2- and 4-door sedans, as well as vans), scan the QR code and you're in. After checking the vehicle over, off you go and you can leave the car in any legal parking place. Everything is done through the app, which is easy to use and works great.

In terms of cost versus a taxi, it comes out about the same, the one disadvantage being that taxis come to you - you don't have to search around for one. Also, you can't sign out from the car outside city limits/their service zone; you're still on the meter until you bring it back. That said, as an alternative to car rental, Traficar is quite a wonder. You can rent a vehicle for 24 hours for only 89zł and none of the common shenanigans of car rental; plus you don't have to pay for gas. You can also drive and drop it off in another Polish city like Warsaw, Wrocław or Katowice where Traficar operates. As such, this is a great option for day and weekend trips, as well as big shopping trips, or simply picking up friends at the airport.

Although you don't need a Polish number or even a Polish licence, you do need a valid driver's license that is recognised in PL. As with regular car rental, citizens from countries that didn't ratify the Vienna Convention on Road Traffic cannot drive on their home licenses; unfortunately this includes Americans, Australians and the Chinese, among others, for whom an International Driver's License is required.