The "Ministerio del Trafico" has a nice information page in English.

Highway Security Notice from Europe Today

Travel in Spain with share a ride

The Spain Travelogues are a good resource for planning your own driving trip.

Public parking is noted by the white "P" surrounded in BLUE. A "P" surrounded with BLACK indicates parking for a special class of people (residents, etc.). Public parking garages can be found in most cities. Hotels often have a parking garage for guests for which an extra fee is usually applied.

Signs, signs everywhere a sign.

On my previous visit to Spain, a U. K. couple told me, "Don't worry about following the road numbers. Just follow the signs that point toward your city destination." For the most part, this is good advice, but knowing a little about the road numbering system can make your drive a little easier. The expressways or "autopistas" are identified by the letter "A" (example, the "A-6") and are toll roads. You can usually avoid the high-cost toll roads by taking non-expressway roads that often parallel the "autopistas". While these roads won't get you to your destination as fast, they do offer a view of Spain you won't get from the expressways.

The sign to the left indicates no entry. This is a sign you will see a lot. Sometimes this sign has a time noted at the bottom, indicating the hours during which the traffic goes two ways.

Street name signs are not always easy to find. To locate a hotel or attraction there usually are signs along the road pointing you in the right direction.

If you are walking down the street, you usually can find a street sign, similar to the one above, mounted on the side of a corner building. These signs are really hard to see from a car.