RENFE calls the two new price bands "Estrella" (-40%) and "Web" (-60%) and they are only applicable to one-way journeys (return tickets have their own, 20% discount, which means it is cheaper to book two separate journeys for there and back if you are booking in advance). The number of low-price seats is limited to so many thousand a day, and the horizon for train ticket purchase is 62 days, so you are not guaranteed their availability unless you catch them as soon as they are put on sale. The low prices are not all that easy to find on the Renfe website, so here is the process to follow.

- Go to Renfe's website - http://www.renfe.es.
- If you are not happy with Spanish, clicking "Seleccione su idioma" at the bottom of the page lets you choose English as your language. The screen lets you see "Timetables and Prices, but clicking "Buy Tickets" takes you straight back into Spanish.
- Whether or not you have selected English, you will now see a search box on the left of the page. Select the radio button "Ida" (one-way), then your starting point from "Principales Estaciones Origen" and your destination from "Principales Estaciones Destino." By way of example, let's say you choose "Madrid" and "Sevilla Santa Justa." You must then select the date for your journey by entering a date as dd-mm-yyy (use either a hyphen or slash as separator, it doesn't matter) or selecting it from the pop-up calendar. You will be shown the trains to your destination for that day* (about twenty a day for the Madrid-Seville journey). The column "Plazas disponibles" shows whether there are seats available in the classes "Turista," "Preferente," and "Club," and the radio button for those tickets disappears anyway if there are no seats available. The basic, "Turista" class offers both kinds of discount (40% or 60%), "Preferente" may offer the lower discount but not (so far as I can tell) the higher one), while there are no discounts for "Club" class.
- Select your train time and ticket class by marking the relevant radio button.
- Scroll down to the bottom of the page. There you will see a CAPTCHA box, which will ask you to prove that you are human and not a robot by entering the characters, a series of numbers. Type them into the box and click "Continuar."
- The next window will show you the train you have selected, its departure time ("Salida"), arrival time ("Llegada"), and the standard ticket price ("Precio") in euros. But before you fill in the rest of your details ("Datos del Comprador") on the page, click the "Tarifa" box. currently showing "General" (full price). The drop-down menu will show the different rates available. As well as the new, "Web" (60%) and "Estrella" (40%) discounts, possible rates are Carnet Joven (young traveller's card, up to 25% discount for holders), "Nino" (child between 4 and 13 years old, 40% discount - younger children travel free, if I am not mistaken), "Tarjeta Dorada" (a card for pensioners, 40% discount - this is not automatic on proof of age, you need to be a card holder).
- As you change the selected "Tarifa," the price shown under "Importe Total del Viaje de ida," and "Importe Total de la Compra" will change. In our example (Madrid-Seville), it will do this:
  General - 71,70 EUR
  Estrella - 43,05 EUR
  Web - 28,65 EUR
- Now you need to fill in your personal details ("Datos del Comprador"), as follows:
     Correo electrónico = e-mail address
     Nombre = First name(s)
     Apellido = Surname
     Apellidio 2 = Maternal surname, you can probably ignore this.
     Tipo de document = the identification you will present - "Pasaporte," passport, NIE (foreign resident's identity card) or "Otro," other.
     Número de documento = document number
     "Dirección" and "Código Postal," address and postcode, ignore if you wish
     "Población" (town or city), "Provincia" (province, state or county would probably do) and "País" (country)
     "Teléfono" (telephone number)
- You will want to uncheck the box saying "Marque esta casilla," etc., unless you want to receive promotional offers by e-mail.
- Accept the conditions by checking the box which says "He leído y acepto las," etc.
- Choose your payment method - Credit or debit card or "puntos."
- Enter your "Número de Tarjeta," card number, "Fecha de Caducidad," expiry date, and "Titular de la Tarjeta," name of the card holder as shown on the card.
- Click "Comprar" (Buy).

That's it, at least as far as I have reached, as I do not really need a train ticket at the moment, so I don't know whether you have the option at any stage to choose your seat, though I imagine not. I expect your payment will be processed and you will be shown a page with a ticket which you will have to print out - don't forget to take it with you, as you may be required to present it (together with your identification document). "Note: RENFE has now modified its booking engine to make low fares slightly easier to find. In the list of all trains available for a particular day, some trains may be marked with a star symbol and/or a "W" symbol. The star indicates that Estrella fares are available, the "W" tells you the lower "Web" rate is available.