Apparently the Spanish “Highway Code” (Codigo de Trafico y Seguridad Vial (pdf)) is about 1000 pages long! (in Spanish of course). So realistically you will not read it and judging by experience not many locals have read it either.
Is it any different in other countries? There will be cause and blame from both locals and foreigners not familiar with Spain’s road laws and of there can be the usual disregard for other road user’s safety.
So what about Roundabouts in Spain?
Drivers here already know one of the most hair-raising driving situations here in Spain is usually at roundabouts. It can sometimes feel more like the fair-ground dodgems and a free-for-all guessing game of lane changing. Of course a lot of drivers do not even signal their intentions (lazy!). So you need to be very careful of other drivers on “glorietas” when driving in Spain.
It should be quite simple: Under normal circumstances you should always exit the roundabout from the right hand lane.
Remember that you must stay to the right and drive as far to the right as possible when travelling around a roundabout in Spain. The right hand lane is the normal driving lane. Try and think of the roundabout as a normal road that has curves. Have a look at the graphic above: Car A and Car B is good driving but C, D and E is bad driving and could impede others drivers or worse still cut-off or force an accident.
If (due to traffic or lane markings approaching the roundabout) you need to enter the roundabout in a left/middle lane then ensure you still move over (and signal) to the right lane in time to exit the roundabout ( like CAR B ).
The principals are similar to the UK rules but of course in Spain we drive on the right.
The main thing is to be very aware of other drivers as unfortunately far too many do not know the above rules… you will be cut-off and will see many near-misses on Spanish roundabouts! Keep calm!