has anyone used BlaBla cars in spain

Yes, but who or what are they and what is the "concept".
An explanation and a link would help.

Blablacar.com

apparently similar to Uber in US. Now expanding thru europe
Seemingly good reviews.

The name doesn't fill me with confidence.

I agree that they could hv found a more responsive name

So you'd be happy getting in a car which has not had to pass any inspection with driver who doesn't have to have any qualifications and may or may not know where they are going - and pay them money?

That's what Uber is - is that what this is too?

Earlier this week I noticed a want ad in the paper in London that Uber was advertising for drivers, specifying that no qualifications would be required.