Bla Bla Car service

Bla Bla Car is not a private car service: it's basically organized hitchhiking. Drivers like you and me offer free seats on their planned drives, in exchange for a contribution to expenses. For a group of 3 on a tourist itinerary, I wouldn't recommend it. Too unreliable and difficult to find three free seats in the same car.

BlaBlaCar also has a bus business, similar to Flixbus.

What cities do you plan to visit? Spain has some extremely fast trains running between major cities, including the Barcelona-Madrid-Cordoba-Seville route. Even if you have some destinations without rail links, the buses are generally quite comfortable.

BlaBlaCar is like Airbnb for cars. You get on the app and look for the date and destination you need. Then you cross your fingers and hope that someone is going your way. It's not a reliable form of transportation unless you truly have no agenda or schedule. Sometimes it works out and sometimes it doesn't. And you have to be OK with riding with random strangers!

We are particularly interested in travel from Toledo to Granada. The train schedule is not often and we would like to arrive in Granada earlier. It looks like I can "book" the ride a few weeks before the departure date. What I am not sure is if the drivers are dependable? How often would there be "no show". How safe is it? Just want to know if anyone has positive or negative experience with this form of travel.

I can only say that I wouldn't do it. If the driver cancels on you late in the game, your chances of finding another ride for 3 people will probably be very, very low. You have no idea about the condition of the vehicle or the quality of the driver. The driver may not be in as much of a hurry as you are; what will you do if he is 2 hours late? The driving route will probably not align with the rail route, so if something goes wrong along the way (car breakdown?), you won't be able to hop on that train that doesn't arrive in Granada as early as you'd like.