There is no end to the variety of buses in Europe. It seems every country has several coach builders that do their own thing using commercial chassis provided by Mercedes, Volvo, MAN and others.
Spain is no exception, although several the following are visitors from other European countries:
-all Barcelona taxis are black with yellow doors and trunk. All makes and models from Seats to Mercedes, Primus to mini-van, must be painted in these colour. They mount the roof light over the passenger side and display a green light for available and red for engaged.
- another open top city tour bus from a competing company (there are two)
- a car (of which there is a huge variety of Euro, Asian and American)
- a tram. These modern looking four car unit trains do street running in some areas but also have dedicated boulevards and stations on some streets such as the Diagonal, a main shopping street.
Another tour bus, a motorbike, which are almost as plentiful as cars, and just so you know you aren't on Mars, a UPS van. Interestingly it does display its IVECO brand name on the grille.
[Now that UPS is in the Maritimes, Mars can't be far behind.]