Book the AVE at least three weeks out — the price difference is not trivial
A Madrid–Granada AVE ticket booked the day before travel regularly costs €65–70. The same seat booked three weeks ahead costs €30–35. Renfe releases cheap fares in batches; they go first for Friday and Sunday trains. Book at renfe.com directly — third-party sites add fees without adding anything useful. If you are flexible, mid-week departures (Tuesday, Wednesday) hold cheap fares longer than weekend trains.