Diesel is NOT called 'gasolina'. Every station near my house says 'diesel' on the pump. Other options are indicated by octane rating, which is typically much higher than in the US. Cheapest is 95, which is what I usually use, and pay 89.9/l. 'Sin Plomo' (unleaded) is 97 octane and Super is 98 and costs around 15% more. Diesel is around 82.8/l.

We just drove from Barcelona to Granada over the holidays and it was around 9 hours with little traffic. We took the freeway down to Valencia and then a national highway over and down to Andalucia, with a stop in Sevilla, one in Cordoba, and another in Granada. FWIW, aside from the Alhambra, Granada is kind of a ****hole. As my friends say, they don't call it Granada for nothing. We saw and did a lot more, in a lot less gentrified/ugly city, in Cordoba.

They DO enforce the speed limits on the highways, and fines are extremely expensive. In addition, the national highways are mostly 2-lane and full of rotundas...don't plan on averaging more than around 60km/h. Lots of trucks.