I used to live in Barcelona, the infrastructure is definitely anti car in every aspect, it's desired to be.
For such a large city, the car traffic is minimal, there are not enough parking opportunities, especially at the beach.
There would be space, but the government knows better, if you have ever been in a tourist destination in Spain during peak season you will know that there is no way to accommodate all the cars.
The only traffic jams you'll encounter is if an accident happened or if you go from Barcelona outwards toward the airport, when commuters go home on Friday afternoons or evening when headed to the nicer , less crowded beaches in the south.
But absolutely nothing compared to London, I have lived there as well and driven a car. It's the city with the worst traffic jams you can imagine, it starts at 7am and never really ends, after 8pm it's quite calm and deserted one weekdays.
But weekends, if you wanna go from the south east to the north, God help you.
It's very bicycle friendly, own parts of the roads, unobstructed by cars. Taxis have a separate lane, and buses as well.
The public transportation is also very good, affordable, you have buses, underground trains, and well, overground trains.
And it's a nice city to walk, the old part of town, the huge parks, really nice.
A role model implementation as far reducing car traffic issues go.
Many people use these electro kind skateboards(forgot name) and scooters. And many people just walk.
Of course , it needs to be mentioned that Barcelona is not built like American suburb areas, it's all apartment blocks of 3-7 stories, all blocks glued together.
It's tight, they even have a convention on how to dry your clothes on balconies and how not to do it.
Barcelona has many other issues, the typical ones for large cities, but transport and car traffic, I haven't seen better in Europe.