I was telling two Catalan friends about my trick of parking at the FGC in Les Planes when we go out to Barcelona at night. It's much faster than going via the Sant Cugat station, you save on the toll and don't need to park in Barcelona.
The addition of only paying for a 1 zone ticket especially appealed to them.
They responded with how they managed to negotiate a lower monthly fee for their teletac.
Competitive money saving is always a good topic here.