To be honest, it depends on your plans. Public transport in central Barcelona works great – the metro connects all areas. But if you're planning day trips to places like Sitges or Montserrat, having a car definitely opens up more possibilities. We ended up renting a car for three days just for trips along the coast. The process of getting the car was simple, and parking wasn't as bad as I expected if you book a spot in advance. Just be careful on the narrow streets of Gracia! If you decide to take that route, you can rent a car in Barcelona at
https://getrentacar.com/en-US/spain/barcelona .