Hi, again Vassiliev.
I asked the question on the other forum and so far have had only one reply, see below
Hi, John, I did a bit of trawling and found this from TripAdvisor posted 2 years ago.
"Problem is most local Spanish hire companies will only hire to a 23-year-old with a minimum of 1 year driving experience.....one or two will allow the age limit to be 21 years old, BUT , charge a premium for this facility.....at 20 years old, I seriously think that you will be pushing it to find any car hire companies that will allow car rental....I can only think of Interrent and Autos Europe ( neither of which are ´´local´´ but are international companies who use local agents).Sorry Sad"
I checked Interrent and it looks like they will rent to younger drivers,
If I get any more replies I will post them here, but I really do advise you to register on the other Forum, you will get a lot of help which may even improve your holiday, providing you ask.